Cellulosic particles, spherical object comprising cross-linked polymer particles, and adsorbent for body fluid purification

ABSTRACT

The present invention relates to a cellulosic particle body comprising interconnected cellulosic small particles with small interparticle spaces and to a method of producing said cellulosic particle body which comprises dispersing cellulosic small particles in an alkaline medium and contacting the resulting suspension with a coagulating solution. In this specification, the above technology will be referred to as the first invention.

TECHNICAL FIELD

[0001] The present invention relates to a cellulosic particle body, amethod of producing said particle body, a spherical type body whichcomprises crosslinked polymer particles interconnected with the aid ofan organic binder comprising a non-crosslinked polymer, a method ofproducing said spherical type body, and an adsorbent for purification ofbody fluids which is capable of removing a target substance at a highspeed in the therapy of hyperlipemia, autoimmune diseases andimmunity-mediated diseases and the like.

BACKGROUND ART

[0002] A cellulosic particle body and a spherical type body comprising acrosslinked polymer particle are in broad use in a variety of fields,for example as a support for immobilization of microbial cells orenzymes, an adsorbent matrix for perfumes and pharmaceuticals, anadsorbent for purification of body fluids, a cosmetic additive, achromatographic stationary phase material, etc. or, thoroughintroduction of a functional group, even as various ion exchangers.

[0003] Much research has been undertaken into the cellulosic particlebody.

[0004] Japanese Kokai Publication Sho-63-90501 discloses a technologywhich comprises blending an anionic water-soluble compound with amixture of viscose and a water-soluble macromolecular compound toprepare a dispersion of microfine particles, coagulating the dispersionunder heating or with the aid of a coagulant, regenerating it with anacid, and removing the water-soluble macromolecular compound through aseries of coagulation, regeneration and aqueous washing to provide aporous microfine cellulosic particle body with a mean particle diameterof not greater than 3×10⁻⁴ m and a maximum pore volume within a porevolume range of 2×10⁻⁸ to 8×10⁻⁷ m, with the total pore volume of allthe pores within said range being not less than 2.5×10⁻⁵ m³/kg. Theparticle body provided by the above technology is such that thecellulosic particle body as such have fine pores.

[0005] Japanese Kokai Publication Sho-63-92602 discloses a technologywhich comprises blending viscose, calcium carbonate and a water-solubleanionic macromolecular compound to prepare a dispersion of finelydivided particles of calcium carbonate-containing viscose, coagulatingand neutralizing the dispersion, and decomposing calcium carbonate withan acid to provide a porous cellulosic particle body.

[0006] With those technologies, however, the cellulosic particle bodyobtained are relatively small in diameter, so that in certainapplications such as a filler, an adsorbent, etc., it is difficult tocarry out a large-scale treatment at a high flow rate and if ahigh-speed treatment is attempted, the cellulosic particle body tend tobe destroyed. Moreover, when such a cellulosic particle body is used forthe treatment of body fluids, plugging with blood corpuscles tend totake place.

[0007] Accordingly there has been a demand for development of acellulosic particle body which would have sufficiently high mechanicalstrength, be compatible with treatment at high flow rates, exploit thepore structure of the cellulosic particle body providing for a largesurface area, and be free from the trouble of plugging in the treatmentof body fluids.

[0008] Meanwhile, in the field of body fluid treatment, a body fluidpurification method is being practiced as a therapeutic techniquecomprising removal of a specific substance(s) from a body fluid, whichcomprises passing the body fluid through an adsorption device packedwith an adsorbent immobilized a substance having an affinity for atarget substance on a carrier to thereby adsorb and remove saidsubstance. The method developed initially for this purpose comprisedpassing whole blood over active charcoal, particularly a coated charcoalparticle to remove a target substance. With advances in plasma perfusionmembranes, various adsorption devices for removing a target substancefrom separated plasma have been developed.

[0009] Generally speaking, in body fluid purification therapy, thetreatment time is preferably as short as possible from the standpoint ofthe patient's quality of life. For reducing the treatment time, severalapproaches may be contemplated by using ingenuity in the aspect ofoperating conditions with the adsorbent material being held unchanged.

[0010] First, it may be contemplated to increase the flow rate of thebody fluid in the extracorporeal circuit so as to increase the volume ofthe body fluid to be contacted with an adsorbent per unit time. However,it will adversely affect the patient's quality of life to excessivelyincrease the flow rate of the body fluid withdrawn from the patient'sbody and circulated extracorporeally. The conventional flow rate of abody fluid for extracorporeal circulation is 0.833×10⁻⁶ to 3.33×10⁻⁶m³/S (50 to 200 ml/min.). Thus, there is a limit to the flow rate of thebody fluid which can be circulated extracorporeally.

[0011] It may also be contemplated to increase the capacity of theadsorption apparatus and thereby prolong the time of contact between thebody fluid and the adsorbent. However, as the device capacity isincreased, the volume of the body fluid existing outside the body duringtreatment is increased to adversely affect the patient's quality oflife, with the result that the device capacity cannot be increasedbeyond a certain limit. The capacity of the conventional adsorptionapparatus for purification of a body fluid is 50×10⁻⁶ to 500×10⁻⁶ m³ (50to 500 ml) at most.

[0012] Then it may also be contemplated to reduce the treatment time byincreasing the static adsorptivity of the adsorption apparatus. Thestatic adsorptivity means the saturated amount of adsorption. As a meansfor enhancing the static adsorptivity, it may be contemplated to enhancethe static adsorptivity by increasing the amount of adsorption per unitadsorbent. The factors influencing the adsorption equilibrium relationare the substance having an affinity for the target substance and thecontact area effective for adsorbing the target substance. However, saidsubstance having an affinity for the target substance is restricted to asubstance having a specific affinity for the particular targetsubstance. Furthermore, it is restricted to a substance substantiallynot affecting the patient's physiology because the objective is thetreatment of a body fluid. It may also be contemplated to increase theeffective contact area but, as the minimum requirement, this contactarea must have pores receptive to the target substance. Therefore, themaximum contact area of the porous body having such pores is limited bythe diameter and number of pores. Thus, there is a limit to enhancingthe static adsorptivity by improving the above-mentioned adsorptionequilibrium relation.

[0013] As mentioned above, because of the restrictions associated withthe body fluid purification technology, it has been found difficult toreduce the treatment time, with the amount of adsorption maintained, byimproving the device capacity, the flow rate of a body fluid, and saidstatic adsorptivity.

[0014] Lastly, it may be contemplated to reduce the treatment time byimproving the dynamic adsorptivity of the adsorption apparatus. Thedynamic adsorptivity means the magnitude of adsorption rate. As a meansfor improving the dynamic adsorptivity, it may be contemplated, forinstance, to improve the dynamic adsorptivity by optimizing the particlediameter of the adsorbent and the intraparticle diffusion coefficient ofthe target substance.

[0015] Referring to the first approach, i.e. the method of reducing theparticle diameter of the adsorbent and, hence, said diffusion distanceto thereby improve the dynamic adsorptivity, reducing the particlediameter of the adsorbent results in a reduced diameter of the fluidflow passageway and an increased pressure loss so that the risk forplugging is increased. Therefore, in consideration of the safety oftherapy, the particle diameter cannot be reduced too much. Actually, theparticle diameter of the conventional adsorbent for plasma perfusion is50×10⁻⁶ m to less than 1000×10⁻⁶ m and that for direct blood perfusionis 100×10⁻⁶ m to less than 4000×10⁻⁶ m.

[0016] Referring to the second approach, that is the method whichcomprises increasing the diffusion coefficient of the target substancewithin the adsorbent for insuring a fast transfer of the targetsubstance within the adsorbent to hereby improve the dynamicadsorptivity, this method is also subject to the following restrictions.In the case of the conventional adsorbent for purification of a bodyfluid which depends on rate-determining diffusion, once the targetsubstance is established, its diffusion coefficient has a constant valueaccording to the structure of the adsorbent so that it becomes necessaryto add ingenuity to the adsorbent structure. However, even if thestructure is optimized, the diffusion coefficient of the targetsubstance within the adsorbent does not increase beyond the diffusioncoefficient in the body fluid where no steric hindrance exists and,therefore, this method is also limited.

[0017] Thus, as far as the conventional adsorbent for purification of abody fluid is concerned, there is a limit to improving the dynamicadsorptivity by increasing the particle diameter of the adsorbent andthe intraparticle diffusion coefficient of the target substance, withthe result that the treatment time can hardly be reduced.

[0018] On the other hand, while it is difficult to apply them to thepurification of a body fluid, there exists some adsorbent materialswhich, when used as chromatographic carriers for immobilization of asubstance having an affinity for the target substance, can be expectedto achieve an improved dynamic adsorptivity.

[0019] The principles relating to dynamic adsorptivity are now explainedin the first place. As an indicator of dynamic adsorptivity, it iscommon practice to use a breakthrough curve which represents the timecourse of change in the concentration of the target substance at theexit of an adsorption apparatus when a solution containing said targetsubstance in a given concentration is passed at a constant flow rate. Inestimating the dynamic adsorptivity of an adsorption apparatus underoperating conditions, it is preferable to keep the linear velocity offlow within the adsorption apparatus constant, that is to say a constantstate of flow around the adsorbent. It should be noted that the term“linear velocity within the adsorption apparatus” is used in thisspecification to mean the rate of transfer (m/s) of the mobile phase inthe adsorption apparatus.

[0020] On the other hand, the theoretical plate number is generally usedas an indicator of the performance of a column packed with an adsorbentnot carrying an adsorbate thereon (a packed column). The theoreticalplate number means the minimum multiples of column height which would berequired for a target substance to attain an adsorption-desorptionequilibrium when a solution containing it is passed through the packedcolumn.

[0021] According to Kato et al. [Shigeo Kato, et el., Journal ofFermentation and Bioengineering, 78, 246 (1994)], the above-mentionedbreakthrough curve representing the dynamic adsorptivity of anadsorption apparatus can be correlated with the above-mentionedtheoretical plate number as an indicator of the performance of a packedcolumn by the following three expressions.$\frac{C}{C_{0}} = {1 - {e^{{- N}\quad \theta}\left\{ {1 + {N\quad \theta} + \frac{\left( {N\quad \theta} \right)^{2}}{2!} + \cdots + \frac{\left( {N\quad \theta} \right)^{N - 1}}{\left( {N\quad - 1} \right)^{!}}} \right\}}}$$t^{-} = \frac{\alpha \quad V}{F}$ $\alpha = \frac{q_{0}}{C_{0}}$

[0022] wherein t represents time (in seconds); C represents theconcentration [kg/m³] of a target substance at the exit of an adsorptionapparatus, which is a time-dependent variable; C₀ represents theconcentration [kg/m³] of the target substance entering the adsorptionapparatus, which is a constant; V represents the volume of theadsorption apparatus or the volume of a packed column [m³], which is aconstant; q₀ represents the amount of adsorption at equilibrium [kg/m³]at C₀, i.e. the amount of adsorption which does not increase any furtherwhen a solution of the concentration C₀ is passed through the adsorptionapparatus, which is a constant; F represents the flow rate [m³/sec.] ofsolution selected so as to be equal to the linear velocity within theadsorption apparatus under operating conditions, which is a constant; Nrepresents the theoretical plate number as found for the targetsubstance when a solution containing it is passed through the packedcolumn at the same flow rate F as that found for the same targetsubstance when the same solution is passed through the adsorptionapparatus, which is a constant; t⁻ represents the average residence time[seconds] of the target substance in the column; θ represents thepercentage of t relative to t⁻; and α is a parameter representing theadsorption efficiency of an adsorbent.

[0023] To demonstrate the influence of the theoretical plate number onthe breakthrough curve, suitable values were substituted into the aboveexpressions for calculation. The result is shown in FIG. 1. Referring toFIG. 1, the amount of adsorption per unit volume q [kg/m³] of theabsorption apparatus up to each point of time t/t⁻ represents the areaabove the breakthrough curve, that is the value which can be found byintegrating {1−(C/C₀)} up to that point of time and dividing the resultby the volume of the adsorption apparatus. FIG. 2 shows the time courseof the absorption amount q with respect to q₀ as calculated by saidintegration. It can be understood from FIG. 2 that the larger thetheoretical plate number of the packed column is, the larger is theadsorption amount which can be adsorbed in a given time and the shorteris the time required for adsorbing a given amount of the substance,indicating that the dynamic adsorptivity of the adsorption apparatus isimproved. It is, therefore, clear that the dynamic adsorptivity of anadsorption apparatus can be improved by increasing the theoretical platenumber of the packed column.

[0024] Furthermore, the theoretical plate number of a packed column isdependent on the minimum column height which is necessary for attainingan adsorption-desorption equilibrium (the height equivalent to atheoretical plate) and the height of the packed column and can beexpressed by the following equation. $N = \frac{L}{HETP}$

[0025] wherein L [m] represents the height of a packed column and HETP[m] represents the height equivalent to a theoretical plate. Since thecolumn height is fixed, increasing the theoretical plate number of thepacked column can be attained by reducing the height equivalent to atheoretical plate which is characteristic of the carrier packed, and thedynamic adsorptivity of an adsorption apparatus can be improved by thismethod. Whereas the theoretical plate number is dependent on the housinggeometry and other factors, the height equivalent to a theoretical plateis a characteristic which is solely dependent upon the properties of theadsorbent or solid phase. Stated differently, in discussing the heightequivalent to a theoretical plate, it is permissible to use a packedcolumn geometrically different from the adsorption apparatus used forconstruction of the breakthrough curve, although the linear velocity offlow in the packed column should be equal to that in the adsorptionapparatus.

[0026] Meanwhile, it is known that when a housing is packed with aparticle having flow-through pores extending through each particle andsub-pores communicating with said flow-through pores and smaller indiameter than the flow-through pores as a stationary phase material forchromatography, a stationary phase material for affinity chromatographyor a support for immobilization of an enzyme and a solution is passedthrough the packing at a suitable flow rate, the migration of a solutewithin the packing is rapid (perfusion effect) compared with the usualparticulate adsorbent not having flow-through pores so that theobjective operation can be accomplished at a high speed [Japanese KohyoPublication Hei-4-500726, Japanese Kohyo Publication Hei-6-507313, N. B.Affean et al.: Journal of Chromatography, 519 (1990), Shigeo Kato etal.: Journal of Fermentation and Bioengineering, 78, 246 (1994)]. Inthis specification, a carrier having a structure such that a flowpassing through its particles occurs when there is a flow around saidcarrier particles and that, when there is a flow of a liquid such as abody fluid around the carrier particles, a portion of the flow passesthrough the carrier particles owing to the resultant pressure gradientis referred to as a perfusion type carrier. The above-mentioned carrierhaving flow-through pores and sub-pores is a perfusion type carrier.

[0027] The perfusion type carrier is known to be a stationary phase witha smaller height equivalent to a theoretical plate. In other words,because of occurrence of flows passing through the carrier particles,the measured height equivalent to a theoretical plate of such aperfusion type carrier is smaller than that of the conventional carrierin which the mass transfer of the target substance depends solely ondiffusion. Therefore, an adsorption apparatus packed with an adsorbentcomprising a substance having an affinity for the target substance asimmobilized on a perfusion type carrier shows an improved dynamicadsorptivity.

[0028] As a typical perfusion type carrier, there is known POROS (tradename), chromatographic carriers available from Perceptive Biosystems(particle diameters 10×10⁻⁶ m, 20×10⁻⁶ m, 50×10⁻⁶ m) (Japanese KohyoPublication Hei-4-500726). However, since those carriers are intended tobe used for chromatography, they are available only in small particlediameter ranges in consideration of the ease of packing and flow.Therefore, when a container is packed with this kind of carrier and afluid from a fermentation tank, a slurry, blood or the like is passedthrough it, plugging tends to take place owing to the small particlediameter. Moreover, in order to attain a perfusion effect, a solutionmust be passed at a high linear velocity of not less than 2.8×10⁻³ m/s.

[0029] Heretofore unknown is a perfusion type carrier which is large inparticle diameter and provides a perfusion effect even when a solutionis passed at a low speed. Neither known to this day is a cellulosicperfusion type carrier. For example, POROS (trade name) mentioned aboveis a carrier comprising conglomerates of fine particles of astyrene-divinylbenzene copolymer.

[0030] On the other hand, porous particles of crosslinked polymers havelarge specific surface areas and have been used broadly aschromatographic column packings or adsorbents and, furthermore, suchparticles have been actively developed. Such conglomerates ofcrosslinked polymer particles may have minute voids between theconstituent crosslinked polymer particles of the conglomerate and,therefore, express a variety of functions not obtainable with discretecrosslinked polymer particles. The following technology is available forthe construction of spherical type bodies or conglomerates having poresbetween the adjacent constituent crosslinked polymer particles.

[0031] Japanese Kokai Publication Hei-9-25303, for instance, discloses amethod for interconnecting particles by way of polymerization whichcomprises polymerizing a monomer on the surface of crosslinked polymerparticles. More particularly, this method comprises dispersingcrosslinked polymer particles in a dispersion medium containing amonomer, polyvinyl alcohol, etc. to let the monomer penetrate into thecrosslinked polymer particles and then polymerizing the monomer tothereby interconnect the crosslinked polymer particles.

[0032] However, because the crosslinked polymer particles are bonded toone another by polymerization, this method requires a complicatedpolymerization procedure and, moreover, is restricted in the diameter ofcrosslinked polymer particles which can be bonded together (100×10⁻⁶ mat most). In addition, since the monomer so polymerized covers up theentire surface of the crosslinked polymer particles, the inherentfunctions of the particles are impaired. Another disadvantage is that,after use, the crosslinked polymer particles cannot be reused.

[0033] The present invention has for its object to provide a carrier oradsorbent which overcomes the above-mentioned disadvantages.

[0034] More particularly, in the light of the above-mentioned arts, itis an object of the present invention to provide a cellulosic particlebody which is suited for use in treatments at high flow rates and hasexcellent mechanical strength and a large surface area and a method ofproducing said particle body.

[0035] In the light of the above-mentioned arts, it is a further objectof the invention to provide a cellulosic particle body which can beprovided in a relatively large particle diameter range and produces aperfusion effect even when a solution is passed at a comparatively lowlinear velocity and a method of producing said particle body.

[0036] In the light of the above-mentioned arts, it is a still anotherobject of the invention to provide a connected particle body comprisingassemblages of crosslinked polymer particles with minute interparticlespaces which (1) can be manufactured by a simpler procedure as comparedwith the prior art, (2) is less restricted in the available particlediameter of assemblages of crosslinked polymer particles as comparedwith the prior art, (3) has an exposed area uncovered by a monomerpolymerized on the surface of crosslinked polymer particles andconsequently allowing expression of the inherent functions of saidparticles, and (4) permits reusing of the crosslinked polymer particlesfrom the assemblages after use.

[0037] It is a still further object of the invention to provide anadsorbent for purification of body fluids which is capable of removing atarget substance at a high speed so as to reduce the treatment time withthe amount of adsorption maintained at a high level.

SUMMARY OF THE INVENTION

[0038] The present invention relates to a cellulosic particle bodycomprising interconnected cellulosic small particles and having voidsbetween particles and to a method of producing said cellulosic particlebody which comprises dispersing cellulosic small particles in analkaline medium and contacting the resulting suspension with acoagulating solution. In this specification, the above technology willbe referred to as the first invention.

[0039] In another aspect, the present invention relates to a perfusiontype cellulosic particle body which comprises porous cellulosic smallparticles interconnected to have void between the cellulosic smallparticles as produced by dispersing the porous cellulosic smallparticles in an alkaline medium to prepare a suspension and contactingthe resulting suspension with a coagulating solution and to a method ofproducing said perfusion type cellulosic particle body which comprisesdispersing porous cellulosic small particles in an alkaline medium andcontacting the resulting suspension with a coagulating solution. In thisspecification, this technology will be referred to as the secondinvention.

[0040] The present invention further relates to a spherical type bodywhich comprises crosslinked polymer particles having diameters within arange of 0.1×10⁻⁶ m to 10×10⁻³ m with a standard deviation of notgreater than 100% of their mean diameter and which has a diameter of1×10⁻⁶ m to 100×10⁻³ m, and satisfies the following conditions (A) to(C):

[0041] (A) that said crosslinked polymer particles are interconnectedvia an organic binder comprising a non-crosslinked polymer;

[0042] (B) that the surfaces of said crosslinked polymer particles havearea(s) not covered with said organic binder but remaining exposed;

[0043] (C) that voids exist between the interconnected crosslinkedpolymer particles.

[0044] The present invention further relates to a method of producingthe spherical type body comprising crosslinked polymer particles whichcomprises immersing crosslinked polymer particles having diameterswithin a range of 0.1×10⁻⁶ m to 10×10⁻³ m with a standard deviation ofnot more than 100% of their mean diameter in a solution containing anorganic binder comprising a non-crosslinked polymer in an organicsolvent which does not dissolve said crosslinked polymer particles butdissolves said organic binder and then evaporating said organic solventunder stirring to interconnect said crosslinked polymer particles viasaid organic binder separating out on surfaces of said crosslinkedpolymer particles.

[0045] The spherical type body mentioned above need only besubstantially spherical and includes a spheroidal body with a ratio ofminor axis/major axis up to about 0.7. In this specification, thistechnology will be referred to as the third invention.

[0046] The present invention relates, in a further aspect, to anadsorbent for purification of body fluids which comprises a perfusiontype carrier and, as immobilized thereon, a substance having an affinityfor a target substance, to an adsorption apparatus for purification ofbody fluids which comprises a housing packed with said adsorbent and toa method of purifying a body fluid using said adsorption apparatus forpurification of body fluids. In this specification, the above technologywill be referred to the fourth invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0047]FIG. 1 is a diagram showing the effect of the theoretical platenumber on the breakthrough curve.

[0048]FIG. 2 is a diagram showing the time course of change in theamount of adsorption relative to q₀.

[0049]FIG. 3 is a photograph (×100) showing the surface of thecellulosic particle body according to Example 1.

[0050]FIG. 4 is a photograph (×100) showing the cross-section of thecellulosic particle body according to Example 1.

[0051]FIG. 5 is a photograph (×1000) showing the cross-section of thecellulosic particle body according to Example 1.

[0052]FIG. 6 is a photograph (×5000) showing the cross-section of thecellulosic particle body according to Example 1.

[0053]FIG. 7 is a photograph (×100) showing the surface andcross-section of the cellulosic particle body according to Example 3.

[0054]FIG. 8 is a photograph (×200) showing the surface andcross-section of the cellulosic particle body according to Example 3.

[0055]FIG. 9 is a photograph (×1000) showing the surface of thecellulosic particle body according to Example 3.

[0056]FIG. 10 is a photograph (×5000) showing the cross-section of thecellulosic particle body according to Example 3.

[0057]FIG. 11 is a photograph (×40) showing the surface of thecellulosic particle body according to Example 6.

[0058]FIG. 12 is a photograph (×40) showing the cross-section of thecellulosic particle body according to Example 6.

[0059]FIG. 13 is a photograph (×500) showing the cross-section of thecellulosic particle body according to Example 6.

[0060]FIG. 14 is a photograph (×5000) showing the cross-section of thecellulosic particle body according to Example 6.

[0061]FIG. 15 is a photograph (×200) showing the surface of thecellulosic particle body according to Example 7.

[0062]FIG. 16 is a photograph (×1000) showing the surface of thecellulosic particle body according to Example 7.

[0063]FIG. 17 is a photograph (×5000) showing the surface of thecellulosic particle body according to Example 7.

[0064]FIG. 18 is an elution curve of low-density lipoprotein inComparative Example 5.

[0065]FIG. 19 is an elution curve of low-density lipoprotein in Example8.

[0066]FIG. 20 is a photograph (×12) showing the surface of the sphericaltype body according to Example 9.

[0067]FIG. 21 is a photograph (×200) showing the surface of thespherical type body according to Example 9.

[0068]FIG. 22 is a photograph (×200) showing the surface of the carrieraccording to Example 10.

[0069]FIG. 23 is a photograph (×5000) showing the surface of the carrieraccording to Example 10.

[0070]FIG. 24 is a photograph (×200) showing the cross-section of thecarrier according to Example 10.

[0071]FIG. 25 is a photograph (×5000) showing the cross-section of thecarrier according to Example 10.

[0072]FIG. 26 is an elution curve of low-density lipoprotein inReference Example 2.

[0073]FIG. 27 is an elution curve of low-density lipoprotein inComparative Reference Example 3.

DETAILED DESCRIPTION OF THE INVENTION

[0074] The first invention is now described in detail.

[0075] The cellulosic small particles mentioned above are particles of acellulosic substance selected from among, for example, cellulose,cellulose derivative and regenerated cellulose.

[0076] The cellulose mentioned above is not particularly restricted butincludes degreased cotton fiber, hemp pulp, wood pulp, and purifiedcelluloses available from said pulps, among others.

[0077] The cellulose derivative mentioned above is not particularlyrestricted but includes a compound containing partially esterifiedhydroxyl groups (ester derivative); a compound containing etherifiedhydroxyl groups (ether derivative), among others.

[0078] The ester derivative of cellulose is not particularly restrictedbut includes cellulose acetate, cellulose propionate, nitrocellulose,cellulose phosphate, cellulose acetate butyrate, cellulose nitrate,dithiocarboxylic esters of cellulose (e.g. viscose rayon), among others.

[0079] The above-mentioned ether derivative of cellulose is notparticularly restricted but includes methylcellulose, ethylcellulose,benzylcellulose, tritylcellulose, cyanoethylcellulose,carboxymethylcellulose, carboxyethylcellulose, aminoethylcellulose andoxyethylcellulose, among others.

[0080] The regenerated cellulose mentioned above is a cellulosicmaterial obtainable by converting cellulose to an easily moldablederivative and reconverting it to cellulose after molding andspecifically includes but is not limited to the various cellulosicmaterials available upon hydrolysis of ester derivatives of cellulosesuch as cellulose acetate and cellulose propionate.

[0081] The cellulosic small particles mentioned above may be porous ornon-porous but is preferably porous. When the cellulosic small particlesare porous, the particles will present with a relatively greater surfacearea per unit volume.

[0082] As the above-mentioned cellulosic small particles, there can beutilized those particles which are conventionally used in applicationssuch as gel filtration stationary phases, cellulosic ion exchangermaterials, stationary phase materials for affinity chromatography,polymer flocculants, adsorbents for purification of body fluids,cosmetic additives, and so on.

[0083] The cellulosic small particles can be produced by theconventional technology. For example, said porous cellulosic smallparticles can be produced by the methods described in Japanese KokaiPublications Sho-63-90501, Sho-63-92602 and so on. More particularly,the following procedures, for instance, can be utilized.

[0084] (1) A basic aqueous polymer solution containing cellulosexanthate and a water-soluble polymer is mixed with a water-solubleanionic polymer to prepare a particle dispersion of basic aqueouspolymer solution, which is then heated or treated with a cellulosexanthate coagulant so as to cause the cellulose xanthate contained inthe dispersion to be coagulated as fine particles. Since those cellulosexanthate particles contain said water-soluble polymer, the polymer isthen removed. Then, the cellulose xanthate particles are neutralizedwith an acid for regeneration of cellulose to provide the objectivecellulosic small particles.

[0085] As an alternative, the coagulation of cellulose xanthate can beeffected by adding an acid to said dispersion. In this case, afterremoval of said water-soluble polymer, the acid added is neutralized forregenerating cellulose to provide the objective cellulosic smallparticles.

[0086] (2) A viscose, calcium carbonate and a water-soluble anionicpolymer are blended to prepare a dispersion of viscose fine particlescontaining calcium carbonate, which is then heated or treated with acoagulant to cause the viscose in said dispersion to be coagulated. Thedispersion is then neutralized with an acid to give fine particles ofcellulose. The cellulose particles are separated from the dispersionand, after removal of the calcium carbonate by acidolysis, dried toprovide the objective cellulosic small particles.

[0087] The mean diameter of said cellulosic small particles ispreferably in the range of 1×10⁻⁶ to 500×10⁻⁶ m. If it is less than1×10⁻⁶ m, it will be difficult to provide sufficient voids among thecellulosic small particles constituting the cellulosic particle body. Onthe other hand, if the upper limit of 500×10⁻⁶ m is exceeded, the greatload of each the cellulosic small particles may not allow the productparticle body to maintain its constituent cellulosic small particles inthe intact agglomerated condition. The more preferred range is 5×10⁻⁶ to100×10⁻⁶ m.

[0088] The cellulosic particle body of the first invention comprises aconglomerate of said cellulosic small particles interconnected so as tohave voids between the cellulosic small particles.

[0089] The voids mentioned above are formed internally of the cellulosicparticle body and, therefore, the cellulosic particle body of the firstinvention is provided with a multiplicity of minute pores, some of whichare exposed on the surface while the others distributed within theparticle body.

[0090] Preferably the cellulosic particle body of the first invention isa conglomerate of cellulosic small particles interconnected in thepresence of a binder. The inventors of the present invention found thatthe interposition of a binder between individual cellulosic smallparticles leads to a marked increase in the strength of the cellulosicparticle body as compared with the corresponding particle body assembledwithout a binder. The use of a binder provides for the additionaladvantage that the strength of the particle body can be controlled byadjusting the amount of the binder.

[0091] The binder mentioned above is not particularly restricted but mayfor example be an organic compound, an inorganic compound, a syntheticorganic low molecular compound, a synthetic inorganic low molecularcompound, a naturally-occurring organic low molecular compound, anaturally-occurring inorganic low molecular compound, a syntheticorganic high molecular compound, a synthetic inorganic high molecularcompound, a naturally-occurring organic high molecular compound or anaturally-occurring inorganic high molecular compound.

[0092] The inorganic compound mentioned above is not particularlyrestricted but may for example be a compound which, upon contact with acoagulating solution, forms a three-dimensional network structure. As anexample of such inorganic compound there can be mentioned water glass.Water glass generally means a concentrated aqueous solution of eithersodium oxide or potassium oxide and silicon dioxide. This solutionreacts with various metal salts to allow growth of a precipitate in thesolution. When cellulosic small particles and water glass (intended tofunction as a binder) are dispersed in an alkaline medium and theresulting suspension is brought into contact with an aqueous solution ofa metal salt (intended to function as a coagulating solution), aprecipitate is formed to give rise to a cellulosic particle bodycomprising interconnected cellulosic small particles.

[0093] The synthetic inorganic high molecular compound is notparticularly restricted but includes inorganic polymer flocculants suchas poly(aluminum chloride), poly(aluminum sulfate), poly(ferricchloride), poly(ferric sulfate) and so on.

[0094] The synthetic organic high molecular compound mentioned above isnot particularly restricted but includes various organic polymerflocculants such as polyacrylonitrile, polyacrylamide, poly(sodiumacrylate) and acrylic acid-acrylamide copolymer, among others.

[0095] The naturally-occurring organic high molecular compound mentionedabove is not particularly restricted but includes, for example,cellulosic substances, starch and starch derivatives, and soluble saltsof alginic acid.

[0096] As the binders mentioned above, among these, substances havingfunctional groups capable of undergoing hydrogen bonding with thehydroxyl groups of the cellulose molecule or cellulose derivativemolecule are preferred. Still more preferred are substances structurallyresembling cellulose. More particularly, cellulosic substances, starchand starch derivatives and soluble salts of alginic acid can bementioned, among others. Those substances have structure similar tocellulose, having glucose structures with attendant hydroxyl groups, sothat they may undergo hydrogen bonding with the hydroxyl groups of thecellulose molecule or cellulose derivative molecule. Those binders arenow described in detail.

[0097] The cellulosic substance mentioned above may be either the samesubstance as or different from said cellulose molecule constituting saidcellulosic small particles, such as cellulose, cellulose derivative,regenerated cellulose molecule and the like.

[0098] The cellulose mentioned just above is not particularly restrictedbut includes the species mentioned hereinbefore.

[0099] The cellulosic derivative mentioned above is not particularlyrestricted but includes the species mentioned hereinbefore.

[0100] The regenerated cellulose mentioned above is not particularlyrestricted but includes the species mentioned hereinbefore.

[0101] The starch and starch derivative mentioned above are notparticularly restricted but include various esters of starch, e.g.acetate ester, succinate ester, nitrate ester, phosphate ester, xanthateester, etc.; various ethers of starch, e.g. allyl ether, methyl ether,carboxymethyl ether, carboxyethyl ether, hydroxyethyl ether,hydroxypropyl ether, etc.; and degradation products of native starch,such as pyrodextrin, starch oxide, etc.

[0102] The pyrodextrin mentioned above is not particularly restrictedbut includes white dextrin, yellow dextrin, and British gum.

[0103] The starch oxide mentioned above is not particularly restrictedbut includes hypochlorous acid-oxidized starch and dialdehyde-starch,among others.

[0104] The soluble salt of alginic acid mentioned above is notparticularly restricted but includes sodium alginate, for instance.

[0105] It is known that an aqueous solution of said soluble salt ofalginic acid forms an insoluble salt when brought into contact with anaqueous solution of a divalent or higher valence metal salt except formagnesium and mercury ions. Since this insolubilization occursinstantaneously, dripping an aqueous solution of a soluble salt ofalginic acid into an aqueous solution of a divalent metal salt such ascalcium chloride results in the easy formation of an insoluble salt. Forexample, when cellulosic small particles and said soluble salt ofalginic acid (intended to function as a binder) are dispersed in analkaline medium and the resulting suspension is contacted with anaqueous solution of a divalent or higher valence metal salt exceptingmagnesium and mercury ions (intended to function as said coagulatingsolution), the insoluble salt is formed to provide said cellulosicparticle body comprising interconnected cellulosic small particles.

[0106] The binders mentioned above, inclusive of said cellulosicsubstances, starch and starch derivatives, can be used eachindependently or in a combination of two or more species.

[0107] It is also possible to use a binder which is a conjugate of twoor more molecules constituting a binder. More particularly, thecopolymer of said synthetic organic high molecular compound with saidnaturally-occurring organic high molecular compound, for example anacrylamide-carboxymethylcellulose graft polymer, can be mentioned by wayof example.

[0108] Referring to said cellulosic particle body, the mode ofinterconnection of individual cellulosic small particles need notnecessarily be covalent bonding but may be any binding mode by which theresulting conglomerate of cellulosic small particles may substantiallyretain its integral form. Thus, in addition to said covalent bonding,the mode of interconnection of cellulosic small particles includes anintertwining of cellulose or cellulose derivative molecules, hydrogenbonding and other modes of chemical bonding.

[0109] For example, cellulose consists of D-glucopyranose unitsconnected by β1→4 glycosidic bonds and has three hydroxyl groups perglucose unit of the backbone chain. Those hydroxyl groups are consideredto be forming hydrogen bonds between molecular chains orintramolecularly and hydrogen bonds between acetal oxygen atoms. In saidcellulose derivatives, too, unsubstituted hydroxyl groups appear to beplaying the same roles.

[0110] When the cellulosic particle body comprises a conglomerate ofcellulosic small particles interconnected in the presence of a binder,the connection by molecular intertwining between the cellulosic smallparticle and the binder, the connection by chemical bonding such ashydrogen bonding between the cellulose small particle, the binder and soon are also included.

[0111] Observation of the mutually connected state of particles in thecellulosic particle body reveals the following three possible cases.

[0112] (1) The adjacent particles are interconnected by point contact oftheir surfaces.

[0113] (2) The adjacent particles adhere each other and areinterconnected by planar contact of their surfaces.

[0114] (3) In appearance, the surfaces of adjacent particles are apartfrom each other but bridged by filamentous or other structures.

[0115] When the cellulosic particle body comprises a conglomerate ofcellulosic small particles interconnected in the presence of a binder,the above state (3) may be included and, in this case, the binder isused as said filamentous or other structures.

[0116] The spaces formed between particles in any of the above threecases are the voids among cellulosic small particles in the cellulosicparticle body according to this invention.

[0117] The preferred mean particle diameter of the cellulosic particlebody of the invention is 10×10⁻⁶ to 5000×10⁻⁶ m and can be judiciouslyselected according to the intended application.

[0118] When the mean diameter of said cellulosic small particles is notless than 1×10⁻⁶ m, the cellulosic particle body comprising suchinterconnectd cellulosic small particles can be a stable particle bodyin the case of a diameter thereof of not less than 10×10⁻⁶ m. When themean particle diameter of the cellulosic particle body is less than10×10⁻⁶ m, the resulting cellulosic particle body may not be stableenough because it has few interconnecting points and is prone todestruction.

[0119] The specific surface area of said cellulosic particle body in drycondition is preferably not less than 2×10⁴ m²/kg. If it is less than2×10⁴ m²/kg, the effective area available for the intended applicationwill be too small. The still more preferred range is not less than 5×10⁴m²/kg.

[0120] The geometry of said cellulosic particle body is not particularlyrestricted provided that it comprises a conglomerate of individualcellulosic small particles interconnected to have voids betweenparticles, thus may for example be spheroidal or substantiallyspherical.

[0121] The cellulosic particle body according to the first invention canbe produced by dispersing said cellulosic small particles in an alkalinemedium and contacting the resulting suspension with a coagulatingsolution.

[0122] The alkaline medium mentioned above is not particularlyrestricted but includes, among others, an aqueous solution of sodiumhydroxide, an aqueous solution of lithium hydroxide, an aqueous solutionof potassium hydroxide, an aqueous solution of cesium hydroxide and anaqueous solution of rubidium hydroxide.

[0123] For adjusting its viscosity, said alkaline medium may besupplemented with a thickener such as glycerin.

[0124] The hydrogen ion concentration of said alkaline medium is notparticularly restricted provided that it is within the alkaline rangebut is preferably not below pH 9. The more preferred pH range is notless than 10 and the still more preferred range is not less than 12.When the pH of the medium is less than 10, contacting said suspension ofcellulosic small particles with the coagulating solution may result in afailure to interconnect the particles with the individual particlesremaining dispersed.

[0125] The pH values mentioned in this specification are values given bypH=−log10[H⁺] assuming that the degree of dissociation of an acid or analkali in aqueous solution=1 and [H⁺]×[OH⁻]=10⁻¹⁴.

[0126] The preferred concentration of said suspension of cellulosicsmall particles is 50 to 75 volume %.

[0127] The above-mentioned concentration of said suspension means thepercentage of the total volume of cellulosic small particles occurringin a suspension based on the volume of the suspension. Here, theconcentration of the residue available upon filtration of the abovesuspension is assumed to be 100 volume %. When the cellulosic smallparticles are porous particles and have a large water content, theirapparent specific gravity is not much different from the specificgravity of the solution so that volume % is substantially equivalent toweight %.

[0128] When the suspension concentration of cellulosic small particlesis less than 50 volume %, contacting droplets of the suspension with acoagulating solution yields a fragment-like cellulosic particle bodywith weak strength. When the concentration exceeds 75 volume %, nosmooth-surfaced liquid droplets are obtained so that the cellulosicparticle body will be a coarse block. The more preferred concentrationis 60 to 70 volume %.

[0129] The suspension mentioned above may be a dispersion of cellulosicsmall particles and a binder in an alkaline medium.

[0130] The method of suspending said binder is not particularlyrestricted but may for example be the method which comprises dissolvingsaid binder in said alkaline medium and blending the resulting solutionor suspension with said cellulosic small particles.

[0131] The proper amount of addition of said binder cannot be stated ingeneral terms because it depends on the molecular weight of the binder,among other factors. Usually, however, the preferred concentration ofthe binder in the suspension of prepared by dispersing cellulosic smallparticles and binder in said alkaline medium is 0.01 to 50 weight %.When the concentration of the binder is less than 0.01 weight %, thebinder does not sufficiently discharge the function of a binder so that,compared with the cellulosic particle body prepared without the aid of abinder, the binder does not contribute in any significant measure to themechanical strength of the cellulosic particle body. When theconcentration exceeds 50 weight %, the excess of the binder mayeliminate the spaces among the constituent cellulosic small particles.The more preferred concentration range is 0.1 to 30 weight % and thestill more preferred range is 0.2 to 20 weight %.

[0132] As mentioned above, the preferred mean diameter of cellulosicsmall particles is 1×10⁻⁶ to 500×10⁻⁶ m. Within this range, the troubleof the binder added filling up the interparticle spaces, which isencountered when the mean particle diameter is smaller than 1×10⁻⁶ m,can be avoided.

[0133] The preferred viscosity of the suspension dispersing saidcellulosic small particles and binder in said alkaline medium at roomtemperature is 5×10⁻⁴ to 1×10⁴ Pa·s. When the viscosity is below 5×10⁻⁴Pa·s, droplets of the suspension contacting the coagulating solutiontend to be deformed so that no spherical type body can be obtained. Whenthe viscosity exceeds 1×10⁴ Pa·s, droplets of the suspension may be hardto be deformed so that a spherical conformation cannot be given.

[0134] The method and apparatus for viscosity measurement are notparticularly restricted provided that any of the conventional techniquesand instruments by the viscosity over the range of 5×10⁻⁴ to 1×10⁴ Pa·scan be determined. The term “viscosity” as used herein means theviscosity defined in JIS Z 8802-1959. Thus, it is the internalresistance of a liquid which is expressed by the magnitude of the straingenerated in the direction of shear rate per unit area in a planeperpendicular to the direction of the shear which exists in the liquidand its dimension is (mass)/(length×time). All viscosities within theabove viscosity range need not be measured with one and the sameapparatus. Moreover, the method and apparatus for viscosity measurementmay be expedient ones, the accuracy of which may for example be about10%.

[0135] The apparatus for viscosity measurement is not particularlyrestricted but includes a capillary viscometer, a short-tube viscometer,a falling-ball viscometer, a tumbling-ball viscometer, afalling-cylinder viscometer, a coaxial-cylinder rotating viscometer, andan air-cell viscometer. When the viscosity of the solution is within therange of 5×10⁻⁴ to 1×10² Pa·s, the air-cell viscometer is preferablyused. The coaxial-cylinder rotating viscometer is preferred fordetermination within the range of 1 to 1×10⁴ Pa·s.

[0136] As said cellulosic small particles are suspended in said alkalinemedium, the cellulose or cellulose derivative becomes alkali celluloseand swells in the surface layer of said cellulosic small particles and,at the same time, the hydrogen bonds are cleaved so that the mobility ofthe cellulose or cellulose derivative molecules is remarkably increased.In case a binder is concomitantly present, the suspension becomes moreready to take up the binder.

[0137] The duration of suspending cellulosic small particles in saidalkaline medium is preferably not less than 1 minute. When it is lessthan 1 minute, it is difficult to insure swelling of the cellulose orcellulose derivative as alkali cellulose on the surface of particles sothat the cellulosic small particles may not be fully interconnected. Themore preferred duration is 1 hour or longer.

[0138] Then, this suspension is brought into contact with a coagulatingsolution, whereby said cellulosic small particles are interconnected.

[0139] Contacting said suspension with said coagulating solution resultsin a marked decrease in the mobility of the cellulose or cellulosederivative molecule so that the intertwining, hydrogen bonding or thelike of the cellulose or cellulose derivative molecules of thecellulosic small particles may take place. Moreover, when a binder isconcomitantly present, the mobility of the binder itself is alsoconsiderably decreased so that the interwining and hydrogen bonding orother bonding between the cellulosic particle and the binder moleculemay take place.

[0140] The coagulating solution mentioned above is not particularlyrestricted provided that it will deprive fluidity of said alkalicellulose or alkali cellulose and binder. Thus, for example, organicsolvents such as ethanol, acetone, etc.; solutions of salts such ascalcium salts; solutions of inorganic acids such as hydrochloric acid,sulfuric acid, phosphoric acid, etc.; organic acids such as acetic acidetc.; and acidic solutions having pH values lower than the pH value ofsaid suspension; and pure water can be mentioned. Those may be used eachindependently or in a combination of two or more species.

[0141] The method of contacting said suspension with said coagulatingsolution is not particularly restricted but includes, among others, themethod which comprises dispersing said suspension in said coagulatingsolution, the method which comprises preparing droplets of saidsuspension and bringing the droplets into contact with said coagulatingsolution; and the method which comprises atomizing said coagulatingsolution into, for example, a mist and causing the mist to contact saidsuspension. Particularly in consideration of the ease of control overthe mean particle diameter of the resulting cellulosic particle body,the method which comprises preparing droplets of the suspension andletting the droplets contact the coagulating solution is preferred.

[0142] When the suspension is formed into droplets ahead of time andcontacted with the coagulating solution, the diameter of said dropletsis preferably not greater than 5×10⁻³ m. When the diameter is greaterthan 5×10⁻³ m, the surface tension is so weak that it is difficult toform the droplets.

[0143] The method of forming said suspension into droplets is notparticularly restricted but includes, among others, the method whichcomprises ejecting said suspension from a capillary device into a gasphase and the method comprising the use of a sprayer. Particularlybecause finely divided droplets can be formed, the use of a sprayer oratomizer is preferred.

[0144] The sprayer mentioned above is not particularly restrictedprovided that the suspension can be atomized into droplets measuring5×10⁻³ m or less in diameter. Thus, for example, a rotary disk sprayer,a pressure nozzle sprayer, and a twin-fluid nozzle sprayer can bementioned.

[0145] The rotary disk sprayer mentioned above is based on the principlethat a liquid dripped onto a disk revolving at a high speed will becentrifugally forced to collide with a gas such as air and be atomized.The mean diameter of the resulting droplets can be easily controlled byadjusting the feeding rate of the liquid and the rotational speed of therotary disk.

[0146] The pressure nozzle sprayer mentioned above is such that a liquidunder high pressure is ejected from small orifices into an ambient gassuch as air to atomize it. The mean diameter of the resulting dropletscan be easily controlled by adjusting the feeding rate of the liquid,the pressure applied, and the diameter of the orifices.

[0147] The twin-fluid nozzle sprayer mentioned above is designed toatomize a liquid by driving it with a high-pressure with use ofcompressed gas, even if a liquid is under low pressure. The meandiameter of the droplets can be easily controlled by adjusting thedelivery rate of the liquid and the ejection speed of compressed gas.

[0148] The diameter of droplets of said suspension can be designed withcomparative ease by judicious selection of a suitable one of theabove-mentioned methods.

[0149] The duration of contact between said suspension and coagulatingsolution is preferably not less than second. When the duration is lessthan 1 second, the cellulosic small particles may not be sufficientlyinterconnected. The more preferred duration is 1 minute or longer.

[0150] The cellulosic particle body of the first invention hasinterparticle voids or spaces and, therefore, presents with a largesurface area relative to the volume of the particles, so that it can beused with advantage as a support for immobilization of microbial cellsor enzymes, a carrier or matrix for adsorption of perfumes andchemicals, and a cosmetic additive, among other uses. Moreover, becauseit has high strength, this cellulosic particle body is amenable tooperations at high flow rates. For those uses, the optimum cellulosicparticle body can be selected with reference to the size, internalstructure of the particle body, and the other factors.

[0151] The above cellulosic particle body may be put to use as it is orused after modification by, for example, filling an inorganic or organicsubstance into said interparticle spaces between the cellulosic smallparticles or reacting the particle body with various substances.

[0152] By the above method of producing said cellulosic particle body,cellulosic small particles can be easily interconnected and, moreover,the required voids between the cellulosic small particles can be easilyprovided. Furthermore, by judicious selection of the method of formingdroplets of the suspension, the mean particle diameter of the productcellulosic particle body can be modulated with comparative easeaccording to the intended use.

[0153] The second invention is now described in detail.

[0154] The alkaline medium for use in the second invention is notparticularly restricted but includes the various media mentionedhereinbefore.

[0155] For adjusting its viscosity, said alkaline medium may besupplemented with glycerin, a water-soluble polymer or the like.

[0156] The preferred pH of said alkaline medium is not less than 13(concentration: not less than 0.1 N). The more preferred pH is 14.3 orhigher (concentration: not less than 2 N). When the pH is less than 13,contacting a suspension containing cellulosic small particles with acoagulating solution results in a dispersion of discrete cellulosicsmall particles, thus failing to form the conglomerate of interconnectedparticles in some cases.

[0157] The cellulosic small particles for use in this second inventionmay be the same cellulosic small particles as those described in detailhereinbefore for the first invention.

[0158] The cellulosic small particles for use in the second inventionare porous particles with a pore diameter suited for the intendedapplication. Such porous cellulosic small particles can be produced bythe method of producing the cellulosic particle body which has beendescribed in detail for the first invention.

[0159] The perfusion type cellulosic particle body of the secondinvention can be produced by dispersing said cellulosic small particlesin said alkaline medium and contacting the resulting suspension with acoagulating solution.

[0160] The duration of dispersing said cellulosic small particles insaid alkaline medium is preferably not less than 1 minute. If it is lessthan 1 minute, it may be found difficult to interconnect said cellulosicsmall particles sufficiently. The more preferred duration is not lessthan 1 hour.

[0161] The suspension concentration of said cellulosic small particlesis preferably 50 to 75 volume %.

[0162] The suspension concentration mentioned above is the percentage ofthe total volume of cellulosic small particles in the suspensionrelative to the volume of the suspension.

[0163] When the suspending concentration of said cellulosic smallparticles is less than 50 volume %, contacting droplets of thesuspension with a coagulating solution yields a fragmentary form ofcellulosic particle body, the strength of which may be low. When theconcentration exceeds 75 volume %, smooth-surfaced droplets can hardlybe obtained and the cellulosic particle body may be a coarse block. Themore preferred range is 60 to 70 volume %.

[0164] The preferred size of said droplets is preferably not greaterthan 3×10⁻³ m in mean diameter. If the mean diameter exceeds 3×10⁻³ m,the surface tension will be so weak that droplets may not be formed.

[0165] The method for forming said suspension into droplets is notparticularly restricted but may for example be the atomizing technologydescribed in detail above for the first invention.

[0166] The coagulating solution mentioned above is not particularlyrestricted but may for example be any of the coagulating solutionsdescribed in detail for the first invention. Among the coagulatingsolutions, use of an acidic solution is preferred.

[0167] The acidic solution mentioned above is preferably a solution witha pH value of 1 or less (concentration: not less than 0.1 N). The morepreferred solution is one having a pH value of −0.3 or less(concentration: not less than 2 N). When the pH exceeds 1, contacting asuspension containing cellulosic small particles with an acidic solutionresults in a dispersion of discrete cellulosic small particles and thedesired conglomeration may not be easily achieved.

[0168] The acidic solution mentioned above is not particularlyrestricted but includes aqueous solutions of HCl, H₂SO₄, HNO₃ and H₃PO₄,etc.

[0169] To adjust its viscosity, said acidic solution may be supplementedwith glycerin, a water-soluble polymer or the like.

[0170] The method of contacting droplets of said suspension with saidcoagulating solution is not particularly restricted but includes, amongothers, the method which comprises dripping said droplets into saidcoagulating solution; the method which comprises atomizing saidcoagulating solution, for example into a mist, and bringing the mistinto contact with said droplets.

[0171] The duration of contacting droplets of said suspension with saidcoagulating solution is preferably not less than 1 minute. If it is lessthan 1 minute, the cellulosic small particles may not be fullyconglomerated. The more preferred duration is not less than 1 hour.

[0172] In the perfusion-type cellulosic particle body of this invention,the mode of interconnection of said cellulosic small particles is notnecessarily covalent bonding but may be any mode of interconnection inwhich the assemblage of individual particles can be maintained in astable manner. For example, the interconnection includes that byintertwining of cellulose molecules and that by chemical bonding such ashydrogen bonding.

[0173] The ratio value of the mean particle diameter of said perfusiontype cellulosic particle body is preferably less than 50 relative to themean diameter of constituent cellulosic small particles. If the valueexceeds 50, the voids between small particles which serve asflow-through pores will be so small that the desired perfusion effect isdecreased.

[0174] The mean particle diameter mentioned above is selected accordingto the intended application. Usually, it is preferably 20×10⁻⁶ to 3×10⁻³m.

[0175] For the application in which a housing is packed with saidperfusion type cellulosic particle body and a solution comparativelyliable to cause plugging is passed, the mean particle diameter of saidparticle body is preferably not less than 100×10⁻⁶ m and the flow rateof the solution is preferably not less than 3×10⁻⁴ m/s within the rangewhich does not cause plugging. When the mean particle diameter is lessthan 100×10⁻⁶ m, plugging tends to take place and when the flow rate isless than 3×10⁻⁴ m/s, the perfusion effect is not sufficient so that theefficiency of operation per unit time will be sacrificed.

[0176] The dried perfusion type cellulosic particle body preferably hasa specific surface area of not less than 2×10⁴ m²/kg by the BET method.If the specific surface area is smaller than 2×10⁴ m²/kg, the effectiveworking area for an application will be too small. The more preferredspecific surface area is not less than 5×10⁴ m²/kg.

[0177] The above perfusion type cellulosic particle body utilizes thecellulosic particle body described in detail hereinbefore. Thisperfusion type cellulosic particle body comprises a plurality ofcellulosic small particles interconnected so as to have voids betweenthe constituent particles, in which said voids between small particlesfunction as flow-through pores while the small pores in the plurality ofinterconnected cellulosic small particles which are open to saidthrough-pores function as sub-pores. The geometry of said particle bodyis usually spheroidal or spherical.

[0178] The perfusion type cellulosic particle body can be used in manydifferent applications by the judicious selection of a porous cellulosicsmall particle and the diameter ratio according to an application. Assuch applications, there may be mentioned gel filtration stationaryphase, cellulosic ion exchanger materials, stationary phase materialsfor affinity chromatography, adsorbent matrices for perfumes andchemicals, supports for immobilization of microbial cells and enzymes,and adsorbent carriers for purification of body fluids.

[0179] The method of producing the perfusion type cellulosic particlebody of the second invention comprises dispersing porous cellulosicsmall particles in an alkaline medium and contacting the resultingsuspension with a coagulating solution to let said cellulosic smallparticles be interconnected so as to have voids between said cellulosicsmall particles.

[0180] According to the above production method, cellulosic smallparticles can be easily interconnected and conglomerated with provisionof voids between particles. Furthermore, since it does not involve theuse of an organic solvent in the course of production and facilitateswashing, the method is very satisfactory in the prevention ofenvironmental pollutions.

[0181] The third invention is now described in detail.

[0182] The representative monomers for use in the preparation of thecrosslinked polymer particles according to the third invention may bestyrene and its derivatives such as α-methylstyrene,chloromethylstyrene, styrenesulfonic acid, etc.; acrylic or methacrylicacid (briefly, (meth) acrylic acid) and their alkyl esters, e.g. methyl(meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, luryl(meth)acrylate, stearyl (meth)acrylate, sulfopropyl (meth)acrylate,2-sulfoethyl (meth)acrylate, hydroxyethyl (meth)acrylate,dimethylaminoethyl (meth)acrylate, polyethylene glycol (meth)acrylate(the degree of polymerization of ethylene oxide=2 to 20), hydroxypropyl(meth)acrylate, polypropylene glycol (meth)acrylate, etc.; vinylacetate, vinylpyridine and its quaternization product; vinylsulfonicacids such as 2-acryloylamino-2-methyl-propanesulfonic acid,2-acrylamido-2-propanesulfonic acid, methacryloyloxypropylsulfonic acid,etc.; vinyl cyanides such as acrylonitrile, methacrylonitrile, etc.; andvinyl halides such as vinyl chloride, vinyl bromide, etc., although theabove is not an exhaustive listing. Those monomers can be used eachindependently or in a combination of two or more species. However, it ispreferable to use styrene as a monomer unit because it can bepolymerized by any of radical polymerization, anionic polymerization andcationic polymerization. These monomers can be polymerized by the knownpolymerization technology in the presence of a crosslinking agent toprovide crosslinked polymers.

[0183] When the monomer has a salt functional group, hydrochloric acid,sulfuric acid, phosphoric acid or an organic acid is used as the counterion to a cationic group, while an alkali metal, ammonia, a lower amine,an alkanolamine or the like is used as the counter ion to an anionicgroup. Those counter ions can be used each alone or in a combination oftwo or more species and, but the above is not an exhaustive listing.

[0184] The crosslinking agent which can be used in the production ofcrosslinked polymer particles includes polyfunctional compounds havingvinyl, hydroxyl, carboxyl, amino, pyridinium, epoxy, isocyanate,mercapto, aldehyde, acid chloride, acid amide or other groups, and thosecrosslinking agents can be used each independently or in a combinationof two or more species. The crosslinking agent includes but is notlimited to aromatic compounds having two or more vinyl groups, such asdivinylbenzene, divinyltoluene, divinylxylene, divinylnaphthalene, etc.Among those compounds, divinylbenzene is preferred in view of its highreactivity to vinyl monomers.

[0185] The crosslinked polymer particles for use in this third inventionare preferably porous. The technology available for the production ofporous crosslinked polymer particles typically comprises conducting asuspension polymerization reaction in a mixture comprising a monomer, acrosslinking agent and a solvent which dissolves the monomer but doesnot dissolve the polymer (non-solvent) and removing the non-solvent fromthe precipitated polymer for utilizing the ghosts as small pores. Theporous crosslinked polymer particles can be used with advantage aschromatographic column packings or various adsorbents in the field ofmedical care.

[0186] The crosslinked polymer particles mentioned above are crosslinkedpolymer particles having particle diameters within the range of 0.1×10⁻⁶to 10×10⁻³ m, preferably 1×10⁻⁶ to 5×10⁻³ m, more preferably 10×10⁻⁶ to1×10⁻³ m. With the crosslinked polymer particles measuring less than0.1×10⁻⁶ m in diameter, the organic binder fills up the voids betweenthe crosslinked polymer particles of the particle body so that theobjective spherical type body of the invention cannot be obtained.Moreover, with crosslinked polymer particles measuring over 10×10⁻³ m indiameter, the great dead load of the crosslinked polymer particlesprevents the particle body from retaining the conglomerate ofcrosslinked polymer particles interconnected by the organic binder inthe intact interconnected condition so that the objective spherical typebody of the invention cannot be obtained.

[0187] The standard deviation of the particle diameter distribution ofsaid crosslinked polymer particles is not greater than 100% of the meanparticle diameter, preferably not greater than 50%. If the standarddeviation exceeds 100%, comparatively smaller crosslinked polymerparticles find their way into the minute voids or spaces between theinterconnected crosslinked polymer particles to cause a non-uniformdistribution of voids, with the result that the favorable functionscharacteristic of the particle body comprising conglomerate ofinterconnected particles, which cannot be obtained with the crosslinkedpolymer particles as such, are not expressed.

[0188] The organic binder comprising a non-crosslinked polymer may be aknown polymer and includes not only polymers of the monomers mentionedabove for the production of said crosslinked polymer particles but alsoethylene-vinyl acetate copolymer and its saponification product orchlorination product, polyethylene and its chlorination product,polybutadiene, polyisoprene, styrene-butadiene copolymer, polyvinylchloride, vinyl chloride-vinyl acetate copolymer, polyurethane,polyethylene, polyethylene oxide, polysulfone, polyamide,polyamideimide, polyimide, cellulose, cellulose acetate, cellulosenitrate, chitosan and its derivatives, melamine resin, epoxy resin andits derivatives, among others. Those binders can be used eachindependently or in a combination of two or more species and, moreover,the above is not an exhaustive listing. The mode of copolymerization maybe any of random, block and graft.

[0189] The organic solvent which does not dissolve said crosslinkedpolymer particles but dissolves said organic binder comprising anon-crosslinked polymer includes but is not limited to ketones such asacetone, methyl ethyl ketone, cyclohexanone, etc.; esters such as methylacetate, ethyl acetate, butyl acetate, ethyl carbonate, etc.; etherssuch as diethyl ether; aromatic hydrocarbons such as toluene, xylene,benzene, chlorobenzene, diethylbenzene, dodecylbenzene, etc.;heterocyclic compounds such as pyridine; saturated hydrocarbons such ashexane, heptane, octane, decane, cyclohexane, etc.; alkyl halides suchas methylene chloride, chloroform, carbon tetrachloride, ethylenechloride, etc.; alcohols such as isoamyl alcohol, hexyl alcohol, octylalcohol, etc.; and other solvents such as 1-nitropropane, dioxane,N,N-dimethylformamide, diethylthioformamide, dimethyl sulfoxide,tetramethylene sulfoxide, acetonitrile, hydroxyacetonitrile,fumaronitrile, cyanoacetic acid, acetic acid, formic acid, ethylenecarbonate, propylene carbonate, ethylene oxalate, γ-butyrolactone,methylene diisocyanate, tetrahydrofuran, and carbon disulfide. Thosesolvents can be used each alone or in a combination of two or morespecies and the above is not an exhaustive listing of the solvents whichcan be used. The amount of said organic solvent is not particularlyrestricted but when the organic solvent is used in an excessive amount,it takes a long time for the solvent to be evaporated after immersionand, therefore, it is preferable to use about 1 to 3 volumes of theorganic solvent per volume of the precipitated crosslinked polymerparticles.

[0190] A typical example of production of the spherical type bodiesdescribed above is given below.

[0191] The spherical type bodies can be produced for example by thefollowing steps I to III.

[0192] Step I

[0193] This is a step in which crosslinked polymer particles measuring0.1×10⁻⁶ to 10×10⁻³ m in diameter with a standard deviation of notgreater than 100% of the mean particle diameter are immersed in asolution of an organic binder comprising a non-crosslinked polymer in anorganic solvent which does not dissolve said crosslinked polymerparticles but dissolves said organic binder.

[0194] Step II

[0195] This is a step following said Step I, in which the above organicsolvent is gradually evaporated off under constant stirring.

[0196] Step III

[0197] In this step, the crosslinked polymer particles areinterconnected through said organic binder precipitating out on thesurface of said crosslinkd polymer particles with the progressivereduction in amount of said organic solvent due to evaporation and, atthe same time, the resulting conglomerates of interconnected particlesare subjected to shearing, tumbling and compaction forces in the courseof stirring to provide a substantially spherical type body.

[0198] By judicious selection of the kinds and amounts of saidcrosslinked polymer particles, said organic binder comprising anon-crosslinked polymer, and said organic solvent which does notdissolve said crosslinked polymer particles but dissolves said organicbinder comprising a non-crosslinked polymer, there can be obtained aspherical type body having the desired interparticle bond strengthand/or a spherical type body in which surface of said crosslinkedpolymer particles is not covered with the organic binder but remainexposed to the desired extent.

[0199] The spherical type bodies comprising the above conglomerates ofcrosslinked polymer particles according to the invention have thefollowing characteristics.

[0200] The first of all is the characteristic that the restriction tothe diameter of interconnected constituent crosslinked polymer particlesis moderate compared with the prior technology. Thus, while the abovespherical type body can be constructed by interconnecting crosslinkedpolymer particles measuring 0.1×10⁻⁶ to 10×10⁻³ m in diameter with astandard derivation of not greater than 100% of the mean particlediameter, there is not a reported case in which crosslinked polymerparticles varying in diameter over such a broad range could ever beenassembled into spherical type bodies according to one and the sametechnological principle.

[0201] Secondly, the above spherical type body is fundamentallydifferent from the conventional spherical type body in that the surfaceof the crosslinked polymer particles has an area(s) not covered with anorganic binder. Thus, by selecting the amount of an organic binderjudiciously, it is possible to have the organic binder distributedexclusively in the voids between the individual crosslinked polymerparticles and to cover the surface of the crosslinked polymer particleor leave it exposed in the desired degree. As a result, there can beprovided a novel spherical type body in which the constituentcrosslinked polymer particles are allowed to express their inherentfunctions sufficiently without being compromized. Furthermore, when thecrosslinked polymer particles are porous particles, the surface porousstructure is not convered up but remains a part exposed so that theadsorptive function of the very porous structure is kept intact.

[0202] Thirdly, the above spherical type body is superior to theconventional spherical type body in the aspect that the crosslinkedpolymer particles can be recovered from the spherical type body forreuse. The conventional spherical type body has to be discarded as it isafter use. In contrast, the spherical type body of the present inventionis such that the organic binder used is soluble in the same organicsolvent as used in the construction of the spherical type body so that,after use of the spherical type body, the constituent crosslinkedpolymer particles can be recovered from the used spherical type body andreuse.

[0203] Having the above favorable characteristics, the spherical typebody of the invention finds application in a broad variety of uses. Forexample, the spherical type body can be used as a column packing forliquid chromatography and a stationary phase for gel permeationchromatography in the field of analytical chemistry. Since the sphericaltype body comprising interconnected crosslinked polymer particlesaccording to the present invention contains interparticle voids, it canbe used as the so-called perfusion type body characterized by flowspassing through the internal body. Thus, compared with fractionalpurification in a chromatographic system using the unitary solidcrosslinked polymer particles of the comparable diameter as thestationary phase, the objective solute can be separated in a shortertime with the spherical type body of the invention.

[0204] The spherical type body of this invention can also be used as theadsorbent in various purification systems in the field of medical carefor the purification of body fluids. Here, the substance having anaffinity for the target substance which is an etiologic agent in a bodyfluid may be occurring in the crosslinked polymer particles constitutingthe spherical type body of the invention, or a substance having anaffinity for the target substance may be immobilized after theconstruction of the spherical type body by interconnecting crosslinkedpolymer particles. As a further alternative, the substance having anaffinity for the target substance may be immobilized after the sphericaltype body of the invention has been coated with a functionalgroup-containing substance.

[0205] The etiologic agent mentioned above includes but is not limitedto low-density lipoprotein, endotoxin, β2-microglobulin, and tumornecrosis factor-α.

[0206] The substance having an affinity for the etiologic targetsubstance in a body fluid is not restricted provided that it has anaffinity for the target substance but includes, among others, substanceshaving negative groups such as sulfo, positive groups such as amino, orhydrophobic groups such as alkyl groups.

[0207] Since the spherical type body of the present invention has aperfusion type characteristic, the time required for body fluidpurification is expected to be reduced.

[0208] The spherical type body of the invention has particle diameterswithin the range of 1×10⁻⁶ to 100×10⁻³ m. Compared with the conventionalperfusion type spherical type bodies measuring 50×10⁻⁶ m at most indiameter, it can be implemented in a remarkably broad particle sizedistribution so that it can be utilized for a detailed investigation ofintra-particle flows in the packed column for chromatography, forinstance.

[0209] The fourth invention is now described in detail.

[0210] The adsorbent for purification of body fluids according to thisinvention comprises a perfusion type carrier on which a substance havingan affinity for a target substance has been immobilized.

[0211] The perfusion type carrier mentioned above must have flow-throughpores having sufficiently large diameters.

[0212] In the adsorbent of this invention, in order that the flowthrough the carrier particle may be created to reduce the heightequivalent to a theoretical plate explained in connection with the priorart in this specification, the ratio of the mean particle diameter ofsaid carrier to the mean diameter of flow-through pores in said carrieris preferably not greater than 70 and more preferably not greater than50.

[0213] In addition, because the adsorbent of this invention is intendedfor purification of a body fluid, it is subject to a certain limit tolinear velocity which is specific to the therapy for purification of theparticular body fluid. Thus, when a column is packed with the perfusiontype carrier of this invention and a solution containing the targetsubstance exclusively is passed at a linear velocity within the range of1×10⁻⁴ m/s to 10×10⁻⁴ m/s, said height equivalent to a theoretical plateas a carrier characteristic is preferably not greater than 0.5 m, morepreferably not greater than 0.1 m.

[0214] The following is a representative method for determination of theheight equivalent to a theoretical plate. A solution containing thetarget substance is injected in a pulsating manner through a columnpacked with the test carrier to construct an elution curve. When thetheoretical plate number is large as it is the case with chromatography,the elution curve assumes a Gaussian distribution and the heightequivalent to a theoretical plate (HETP) can then be calculated by meansof the following equation.${HETP} = \frac{L}{\text{5.54}\left( \frac{T_{r}}{W_{t}} \right)^{2}}$

[0215] wherein L [m] represents a packed column height, Tr [sec]represents a retention time, and Wt [sec] represents a half-time width.The retention time means the time at which the peak height (top) of theelution curve is detected and the half-time width means the time widthcorresponding to half of the peak height [F. Guaise: Optimization ofLiquid Chromatography, Kodansha, p.18 (1980)].

[0216] However, unlike in chromatography, the particle diameter of theadsorbent for purification of body fluids is large and the length of thehousing is limited so that the elution curve of a target substance asconstructed using the housing packed with the adsorbent for purificationof body fluids seldom assumes as Gaussian distribution. In such cases,the shape of the elution curve can be used as a qualitative indicator ofthe adsorbent performance.

[0217] When the mass transfer is insufficient, i.e. the heightequivalent to a theoretical plate is large and the theoretical platenumber is small, a large proportion of the target substance cannot bebrought into sufficient contact with the carrier but be eluted alongwith the flow of the solution introduced into the housing. Therefore,the peak top position occurs immediately after emergence of that volumeof the solution corresponding to the interparticle void volume of thecarrier and thereafter the target substance is gradually eluted with theprogress of elution time.

[0218] On the other hand, when the mass transfer is efficient, i.e. theheight equivalent to a theoretical plate is small and the theoreticalplate number is large, the better the mass transfer is, the greater thefrequency of the target substance contacting the adsorbent is.Therefore, the time during which the target substance remains in thehousing is prolonged and the peak immediately following completion ofemergence of the volume of the solution corresponding to theinterparticle void volume of the adsorbent bed is small and the peak topposition is also shifted backwards. Moreover, the elution curve becomescloser to a Gaussian curve.

[0219] In the present invention, the geometry of the flow-through poresin said carrier particles need only be such that a portion of the flowin the housing may pass through the carrier particles and the shape andnumber of pores are not particularly restricted. For example, thecross-sectional configuration may be circular, polygonal or amorphous.Moreover, the flow-through channels within the carrier particles may belinear or curved. In addition, a plurality of flow-through porespreferably exist and the flow-through pores may be similar or differentin geometry and extending in parallel or in random directions.

[0220] The carrier may have a construction such that when a body fluidflows around it, a flow of the body fluid passing through its interiorpores may occur. Moreover, said carrier may be in any of particulate,slab-like and amorphous forms but is preferably particulate from thestandpoint of the ease of passage and handling.

[0221] The carrier mentioned above is not particularly restricted butmay for example be a porous carrier having flow-through pores, agranular carrier manufactured by agglomerating fine particles, agranular carrier manufactured by assembling fibers, or a granularcarrier processed to have flow-through pores. The fine particles orfibers for use in the manufacture of said granular carrier arepreferably those having small pores receptive to the target substance;i.e. having a large contact area for adsorption. The granular carrier tobe processed to have flow-through pores as mentioned above may alsopreferably be made of a material having a multiplicity of small poresreceptive to the target substance even before processed.

[0222] The carrier preferably has a sufficient strength so that it willnot be compacted to undergo deformation of particles to the extent ofinterfering with passage of the body fluid.

[0223] The technology for manufacturing said carrier includes the methodwhich comprises agglomerating particles to provide flow-through pores,the method which comprises assembling fibers, the method which comprisesprocessing granules or particles to have pores, and so on. As toexamples of the method for assembling particles or fibers, there can bementioned the technique of effecting assembling during a polymerizationreaction for producing the particles or fibers and the technique whichcomprises subjecting only the mutually adjoining surfaces of particlesor fibers, without destroying the structure of particles or fibers, to atreatment with an organic solvent, heat, an adhesive, an acid, analkali, etc. to bond them together. The spaces between the agglomeratedparticles or fibers constitute flow-through pores. The technology forprocessing particles to have pores includes laser drilling, solventleaching and the like.

[0224] The material for said carrier includes native macromolecularsubstances such as cellulose, chitin, chitosan, agarose, etc.;modification products of native substances, such as acylcelluloses,acylchitins, etc.; synthetic polymers such as polystyrene,polymethacrylic acid and its derivatives and their copolymers, polyvinylalcohol, styrene-divinylbenzene copolymer, etc.; and inorganic materialssuch as glass, alumina, ceramics, and so on.

[0225] Furthermore, as said carrier, the perfusion type cellulosicparticle body of the second invention or the spherical type bodiescomprising crosslinked polymer particles according to the thirdinvention can also be used with advantage.

[0226] The target substance mentioned above includes not only theetiologic agents mentioned by way of example in connection with thethird invention, but also other lipoproteins which may be causative ofatherosclerosis such as very low density lipoproteins; immunoglobulins(A, D, E, G, M), anti-DNA antibodies, anti-acetylcholinereceptor-antibodies, anti-blood group antibodies, anti-platelet antibodyand other autoantibodies and antigen-antibody complexes; rheumatoidfactors, macrophages, invasive carcinoma T-cells, and so on.

[0227] The substance having an affinity for said target substance is notparticularly restricted provided that it is capable of adsorbing thetarget substance. Although this has been explained in connection withthe third invention, a further discussion seems in the following. Thus,the affinity between a substance having an affinity for a targetsubstance and the target substance is classified into a biologicalaffinity and a physicochemical affinity. The substance exhibiting anaffinity for a target substance by way of biological interactionincludes a substance on which an antigen has been immobilized, asubstance on which an antibody has been immobilized, a substance whichutilizes a biological interaction such as complement fixation or Fccoupling, and so on. The substance exhibiting an affinity for a targetsubstance by way of physical interaction includes a substance whichutilizes an electrostatic interaction, a substance which utilizes ahydrophobic interaction, and etc. Among them, a substance exhibiting anaffinity for the target substance by way of physical interaction ispreferred in consideration of availability of materials, stability ofthe activity during the manufacture, sterilization, storage andtransport of the adsorbent and column, and the risk for adversereactions when contacted with blood.

[0228] To describe the substance exhibiting an affinity for the targetsubstance by way of physical interaction in further detail, substanceshaving negative groups can be used for adsorbing low densitylipoprotein, for instance. The substances having negative groups includesulfated polysaccharides such as dextran sulfate, heparin sulfate,chondroitin sulfate, chondroitin polysulfate, heparitin sulfate, xylansulfate, caronin sulfate, cellulose sulfate, chitin sulfate, chitosansulfate, pectin sulfate, inulin sulfate, arginic acid sulfate, glycogensulfate, polylactose sulfate, carragenin sulfate, starch sulfate,polyglucose sulfate, laminaran sulfate, galactan sulfate, levan sulfate,mepesulfate, etc.; phosphotungstic acid, polysulfated anethol, polyvinylalcohol sulfate, polyphosphoric acid, and polyacrylic acid. Among them,sulfated polysaccharides are particularly effective. Further, asfavorable examples from clinical points of view, heparin and dextransulfate can be mentioned.

[0229] The above substances having negative groups are examples of thesubstance exhibiting an affinity for a target substance by way ofphysical interaction and finding application in the adsorption oflow-density lipoprotein but depending on the specific target substance,substances having positive and hydrophobic groups and exhibitingphysical interactions can also be used. Moreover, a plurality ofdifferent substances each having an affinity for the target substancemay be immobilized. Aniline may also be mentioned as an example of saidsubstance having an affinity for the low-density lipoprotein fraction.

[0230] The technology for immobilizing said substance having an affinityfor the target substance on a carrier or support includes various knownmethods such as covalent bonding, ionic bonding, physical adsorption,embedding, and insolubilization of precipitation on the surface andthose methods can be selectively used according to the particularsubstance having an affinity for the target substance and the kind ofcarrier material. In consideration of the loss by release of thesubstance having an affinity for the target substance in thesterilization procedure, the immobilization by covalent bonding ispreferred. If necessary, a spacer may be interposed between the carrierand the substance having an affinity for the target substance.

[0231] The technology which can be used to render the carrier reactiveto the substance having an affinity for the target substance in theimmobilization of said substance having an affinity for the targetsubstance on said carrier by covalent bonding includes the cyanogenhalide method, epichlorohydrin method, bis-epoxide method, andbromoacetyl bromide method, among others. As the specific groups whichcan be used in the above reaction, there can be mentioned amino,carboxyl, hydroxyl, thiol, acid anhydride, succinylimido, chloro,aldehyde, epoxy, tresyl and other groups. From the standpoint ofstability in heat sterilization, the epoxy group derived from theepichlorohydrin method is particularly preferred.

[0232] The preferred adsorbent for purification of body fluids accordingto the fourth invention has a mean particle diameter of not less than100×10⁻⁶ m and a perfusion effect obtained when a housing is packed withthis adsorbent and a solution is passed at a linear velocity of not lessthan 3×10⁻⁴ m/s.

[0233] When the above adsorbent for purification of a body fluid iscontacted with whole blood, consideration of the possible plugging withblood corpuscles and the dynamic adsorption performance that may beobtained suggests that the particle diameter of the adsorbent ispreferably 100×10⁻⁶ m to less than 4000×10⁻⁶ m, more preferably 100×10⁻⁶m to less than 600×10⁻⁶ m.

[0234] When the body fluid to be treated is whole blood, the adsorbentmust have a sufficiently large particle diameter for securing pathwaysfor blood corpuscles etc. as compared with the case when a liquid suchas plasma is passed. However, when the conventional carrier is used, thediffusion distance increases as the particle diameter is increased,whereby the dynamic adsorptivity of the adsorbent is decreased. Thisdynamic adsorptivity is particularly poor when the conventionaladsorbents of increased particle diameters are used for the treatment ofwhole blood.

[0235] On the other hand, in the adsorbent for purification of a bodyfluid according to the fourth invention, the carrier produces aperfusion effect so that the mass transfer is improved as compared withthe conventional carrier in which the mass transfer of the targetsubstance is solely dependent on diffusion. Therefore, the adsorbent forpurification of a body fluids according to this invention within theparticle diameter range of 100×10⁻⁶ m to less than 4000×10⁻⁶ m,preferably 100×10⁻⁶ m to less than 600×10⁻⁶ m, shows a remarkablyimproved dynamic adsorptivity when contacted with whole blood.

[0236] The adsorption apparatus comprising a housing packed with anadsorbent for purification of a body fluid which is said perfusion typecarrier carrying as immobilized thereon a substance having an affinityfor the target substance is also included in the scope of the presentinvention.

[0237] The method of using said adsorption apparatus is similar to thatof using the adsorption apparatus for adsorption of a body fluid whichis conventionally used in a plasma perfusion system or a direct bloodperfusion system. The method can be carried into practice in theconventional manner, for example with sustained injection of ananticoagulant into the body fluid circuit for preventing coagulation ofthe body fluid and provision of a pressure probe for sensing theoccurrence of circuit plugging.

BEST MODE FOR CARRYING OUT THE INVENTION

[0238] The following examples are intended to illustrate the presentinvention in further detail and should by no means be construed asdefining the scope of the invention.

EXAMPLE 1

[0239] Carboxymethylcellulose (Wako Pure Chemical Ind.) was mixed with 6N-sodium hydroxide/water (pH=14.8) to prepare a 5.6 weight % aqueouscarboxymethylcellulose solution. Then, porous cellulose small particleshaving a mean diameter of 25×10⁻⁶ m (Chisso Corporation) were mixed withthe above carboxymethylcellulose-containing aqueous sodium hydroxidesolution (suspension concentration 65 vol. %, the binder fraction 2.0wt. %) for 5 hours under constant stirring. Then, using a micropipetwith a tip diameter of 0.5×10⁻³ m, the suspension was dripped intocontact with 99.5% ethanol solution, whereby a substantially sphericalcellulosic particle body was obtained. The diameter of the particle bodywas about 0.6×10⁻³ to 1×10⁻³ m. When this spherical cellulosic particlebody was rinsed with pure water and shaken in pure water, the particlebody retained its original shape. No deformation of the particle bodyoccurred, either, when the above cellulosic particle body was heldbetween the thumb and the index finger and rolled over a distance ofabout 5×10⁻³ m for 5 reciprocations by rubbing the fingers against eachother in the lengthwise direction. The pH value was calculated by meansof the equation pH=−log₁₀ [H⁺] assuming the degree of dissociation ofthe aqueous solution of sodium hydroxide and an aqueous solution ofHCl=1 and [H⁺]×[OH⁻]=10⁻¹⁴. The same applies to the pH values givenhereinafter.

[0240] Pure water was substituted for the liquid within the abovecellulosic particle body obtained and after ethanol substitution,substitution with 2-methyl-2-propanol was further carried out. Theparticle body was then lyophilized using a freeze-dryer (Eiko Eng. Co.,Ltd.) and after vapor deposition of gold, the lyophilizate was examinedwith a scanning electron microscope (Topcon). As shown in FIG. 3, theresulting cellulosic particle body was substantially spherical.Furthermore, voids were observed between the interconnected cellulosicsmall particles as shown in FIGS. 4 and 5. Moreover, as can be seen inFIG. 6, the pores which had existed in the constituent porous cellulosicsmall particles were still observed even after interconnection.

EXAMPLE 2

[0241] A porous cellulosic small particle having a mean particlediameter of 25×10⁻⁶ m (Chisso Corporation) were mixed with 6 N-sodiumhydroxide/H₂O (pH=14.8) (suspending concentration 62 vol. %; the binderfraction 0.0 wt. %) for 5 hours with constant stirring. Then, using amicropipet with a tip diameter of 0.5×10⁻³ m, the suspension was drippedinto contact with 6N—HCl/H₂O (pH=−0.8), whereby a substantiallyspherical cellulosic particle body was obtained. The diameter of thisparticle body was about 1×10⁻³ m.

[0242] The cellulosic particle body obtainable by this productiontechnology, wherein a binder is not used, did not lose its shape evenwhen it was washed with pure water and shaken in pure water. However,this particle body failed to retain its shape when it was held betweenthe thumb and the index finger and rolled over a distance of about1×10⁻³ m by rubbing the fingers against each other in their lengthwisedirection.

EXAMPLE 3

[0243] Carboxymethylcellulose was mixed with 6N-sodium hydroxide/H₂O(pH=14.8) to prepare a 5.6 wt. % of carboxymethylcellulose solution.Then, a porous cellulose small particle having a mean particle diameterof 25×10⁻⁶ m (Chisso Corporation) was contacted with the above solutionof carboxymethylcellulose in sodium hydroxide/H₂O (suspensionconcentration 63 vol. %, the binder fraction 2.0 wt. %) for 5 hoursunder constant stirring. Then, using a twin-fluid nozzle means (havingan inner and an outer nozzle in concentric relation), compressednitrogen gas was ejected from the outer nozzle while the abovesuspension was dispensed in a mist form from the inner nozzle. Thedelivery rate of nitrogen gas was 3.3×10⁻⁴ m³/s and the dispensing rateof the suspension was 1.1×10⁻⁷ m³/s. The diameter of the inner nozzle ofsaid twin-fluid nozzle means was 2.6×10⁻³ m and the diameter of theouter nozzle was 4.4×10⁻³ m. The delivery head was 4 m. Using 99.5%ethanol as a coagulation bath, droplets of said suspension were mixedwith the bath, whereby the cellulosic particle body of the invention wasformed in the coagulation bath. The mean diameter of the particle bodywas about 2×10⁻⁴ m. When the cellulosic particle body thus obtained wasrinsed with pure water and shaken in pure water, each particle bodyretained its original shape.

[0244] Substitution of pure water for the liquid within the cellulosicparticle body thus obtained was followed by ethanol substitution and,then, substitution with 2-methyl-2-propanol was carried out. Theparticle body was then lyophilized with a freeze dryer (Eiko Eng. Co.,Ltd.) and after vapor deposition of gold, the particle body was examinedusing a scanning electron microscope (Topcon). The cellulosic particlebody obtained as above was substantially spherical and voids wereobserved between the interconnected cellulosic small particles.Furthermore, the pores which had been available in the constituentporous cellulosic small particles could be still observed even afterinterconnection.

EXAMPLE 4

[0245] Sodium alginate (Wako Pure Chemical Ind.) was mixed with6N-sodium hydroxide/H₂O (pH=14.8) to prepare a 3.6 wt. % sodium alginatesolution. A porous cellulose small particle having a mean particlediameter of 25×10⁻⁶ m (Chisso Corporation) was contacted with the abovesodium alginate solution in NaOH/H₂O (suspension concentration 65 vol.%, the binder fraction 1.3 wt. %) for 6 hours under constant stirring.Then, using a micropipet having a tip diameter of 0.5×10⁻³ m, dropletsof the above suspension were brought into contact with 6N-calciumchloride/H₂O, whereupon a substantially spherical cellulosic particlebody was obtained. The diameter of the particle body was about 0.7×10⁻³m. This cellulosic particle body retained its shape even when rinsedwith pure water and shaken in pure water. The particle body fullyretained its shape even when it was held between the ventral sides ofthe thumb and index finger and rolled over a distance of about 5×10⁻³ mfor at least 5 reciprocations by rubbing the fingers against each otherin their lengthwise direction.

[0246] Following substitution of pure water for the liquid within thecellulosic particle body thus obtained, ethanol substitution and, then,substitution with 2-methyl-2-propanol were carried out. It was thenlyophilized with a freeze-dryer (Eiko Eng. Co., Ltd.) and, after vapordeposition of gold, examined using a scanning electron microscope(Topcon). As can be seen in FIG. 7, which is a sectional view of thecellulosic particle body, the particle body was substantially spherical.It can also been in FIGS. 8 and 9 that the particle body contained voidsbetween the interconnected constituent cellulosic small particles.Furthermore, as shown in FIG. 10, the pores which had been availablewithin the constituent cellulosic small particles were still observedeven after interconnection.

EXAMPLE 5

[0247] J Sodium Silicate No. 3 (a concentrated aqueous solution ofsodium oxide and silicon dioxide (water glass), Nippon Kagaku Kogyo) wasmixed with 6N-sodium hydroxide/H₂O (pH=14.8) to prepare a 30.6 wt. %solution of J Sodium Silicate No. 3. Then, a porous cellulose smallparticle having a mean particle diameter of 25×10⁻⁶ m (ChissoCorporation) was contacted with the above solution of J Sodium SilicateNo. 3 in sodium hydroxide/H₂O (suspension concentration 62 vol. %, thebinder fraction 11.6 wt. %) for 6 hours under constant stirring. Then,using a micropipet having a tip diameter of 0.5×10⁻³ m, the abovesuspension was dripped into contact with 6N-calcium chloride/H₂O,whereupon a substantially spherical cellulosic particle body wasobtained. The diameter of each particle body was about 0.5×10⁻³ m. Thiscellulosic particle body retained its shape fully when rinsed with purewater and shaken in pure water. Moreover, the particle body fullyretained its shape even when it was held between the ventral sides ofthe thumb and index finger and rolled over a distance of about 5×10⁻³ mfor at least 5 reciprocations by rubbing the fingers against each otherin their lengthwise direction.

[0248] Following substitution of pure water for the liquid within thecellulosic particle body obtained above, ethanol substitution andsubstitution with 2-methyl-2-propanol were serially carried out. It wasthen lyophilized with a freeze-dryer (Eiko Eng. Co., Ltd.) and, aftervapor deposition of gold, examined using a scanning electron microscope(Topcon). As a result, the cellulosic particle body was found to besubstantially spherical. There also were observed voids between theinterconnected cellulosic small particles and, even afterinterconnection, the pores available in the constituent porouscellulosic small particles were still observed.

EXAMPLE 6

[0249] A porous cellulose small particle having a mean particle diameterof 20×10⁻⁶ m (Chisso Corporation) was suspended in 6N-sodiumhydroxide/H₂O (pH=14.8) at a final concentration of 70 vol. %. Thesuspension was thoroughly agitated with a stirrer and using a capillarypipet having a tip diameter of 0.7×10⁻³ m, the above suspension wasdripped into contact with 5N—HCl/H₂O (pH=−0.7), whereupon a cellulosicparticle body was obtained.

[0250] The diameter of each particle body was about 2×10⁻³ m. Thecellulosic particle body thus obtained was rinsed with pure water.

[0251] Following substitution of ethanol for the liquid within the abovecellulosic particle body, substitution with 2-methyl-2-propanol wascarried out. The particle body was then lyophilized using a freeze-dryer(Eiko Eng. Co. Ltd.) and, after vapor deposition of gold, thelyophilizate was examined with a scanning electron microscope (Topcon).As a result, this cellulosic particle body was found to be substantiallyspherical as shown in FIG. 11. In addition, as is evident in FIG. 13,there were voids between the interconnected cellulosic small particles.Furthermore, the pores available in the constituent porous cellulosicsmall particles were still observed even after interconnection as shownin FIG. 14.

COMPARATIVE EXAMPLE 1

[0252] A porous cellulosic small particle having a mean particlediameter of 20×10⁻⁶ m was suspended in pure water at a finalconcentration of 70 vol. %. The suspension was thoroughly agitated witha stirrer and using a capillary pipet having a tip diameter of 0.7×10⁻³m, the suspension was dripped into contact with 5N—HCl/H₂O (pH=−0.7),whereupon the cellulose particles were simply dispersed.

COMPARATIVE EXAMPLE 2

[0253] A porous cellulosic small particle having a mean particlediameter of 20×10⁻⁶ m (Chisso Corporation) was suspended in 6N-sodiumhydroxide/H₂O (pH=14.8) at a final concentration of 70 vol. %. Afterthorough agitation with a stirrer, the suspension was dripped from acapillary pipet with a tip diameter of 0.7×10⁻³ m into contact with purewater, whereupon disk-shaped masses of cellulose were obtained. Uponshaking, the disks collapsed to give a dispersion of discrete celluloseparticles.

COMPARATIVE EXAMPLE 3

[0254] A porous cellulose small particle having a mean particle diameterof 20×10⁻⁶ m (Chisso Corporation) was suspended in 6N-sodiumhydroxide/H₂O (pH=14.8) at a final concentration of 40 vol. %. Thesuspension was thoroughly agitated with a stirrer and using a capillarypipet with a tip diameter of 0.7×10⁻³ m, droplets of the suspension weremixed with 5N—HCl/H₂O (pH=−0.7), whereupon fragment-like masses ofcellulose were obtained. When shaken, those masses collapsed, giving adispersion of discrete cellulose particles.

COMPARATIVE EXAMPLE 4

[0255] A porous cellulose small particle having a mean particle diameterof 20×10⁻⁶ m (Chisso Corporation) was suspended in 6N-sodiumhydroxide/H₂O (pH=14.8) at a final concentration of 80 vol. %. Thesuspension was thoroughly agitated with a stirrer and using a capillarypipet with a tip diameter of 0.7×10⁻³ m, the suspension was dripped intocontact with 5N—HCl/H₂O (pH=−0.7). As a result, smooth-surfaced dropletscould not be formed but the resulting cellulosic masses were massiveform.

EXAMPLE 7

[0256] A porous cellulose small particle with a mean particle diameterof 20×10⁻⁶ m (Chisso Corporation) was suspended in 6N-sodiumhydroxide/H₂O (pH=14.8) at a final concentration of 70 vol. % and theresulting suspension was agitated well with a stirrer. Using atwin-fluid nozzle means (having an inner and an outer nozzle inconcentric relation), compressed nitrogen gas was ejected from the outernozzle while the above suspension was dispensed from the inner nozzle.The nitrogen ejection pressure was 5×10³ kg m² and the suspensiondispersing speed was 5.19×10⁻⁴ m³/s. The diameter of the inner nozzle ofthe above twin-fluid nozzle means was 2.6×10⁻³ m and the diameter of theouter nozzle was 4.4×10⁻³ m. The delivery head was 4 m. As a result, theobjective cellulosic particle body was obtained in an acidic solution.The mean particle body diameter was about 200×10⁻⁶ m.

[0257] Following substitution of ethanol for the liquid within the abovecellulosic particle body, substitution with 2-methyl-2-propanol wascarried out. It was then lyophilized with a freeze-dryer (Eiko Eng. Co.,Ltd.) and, after vapor deposition of gold, the particle body wasexamined using a scanning electron microscope (Topcon). As shown in FIG.15, this cellulosic particle body was spherical. As can be seen in FIG.16, voids were available between the interconnected cellulosic smallparticles. It can also be seen in FIG. 17 that the pores originallyavailable in the constituent cellulose particles were still evidentafter interconnection.

COMPARATIVE EXAMPLE 5

[0258] A column (in. dia. 0.01 m, 0.05 m long) was packed with a porouscellulosic small particle (mean particle diameter 179×10⁻⁶ m) (ChissoCorporation) which is of the same structure (e.g. pore diameter) as thecellulose particles used in Examples 6 and 7 and Comparative Examples 1to 4 but different in mean particle diameter. Then, physiological salineat 23.2% (Otsuka Pharmaceutical Co.) was passed through the column at alinear velocity of about 5×10⁻⁴ m/s and 100×10⁻⁹ m³ of a 5-fold dilutionof a low-density lipoprotein reagent (L-2139, SIGMA) in physiologicalsaline was injected in a pulsating manner. The time course of change inthe concentration of low-density lipoprotein was monitored with anabsorptiometer (ATTO) at the wavelength of 280 nm. As shown in FIG. 18,the peak top was confirmed to occur in the position immediatelyfollowing the beginning of elution. The cellulosic particles used hadpores receptive to the low-density lipoprotein. Therefore, the abovecharacteristics of the elution curve were not attributable to theabsence of pores through which low-density lipoprotein could enter thecellulosic particle body but rather attributable to the fact thatbecause the particle size of the particle body was large, the masstransfer distance was long and, therefore, the low-density lipoproteincould not migrate sufficiently within the cellulosic particle body butwas eluted out from the column exit together with the flow down in theinterstices of the cellulosic packing.

EXAMPLE 8

[0259] A column (0.01 m in. dia., 0.05 m long) was packed with theparticle body obtained in Example 7 (the mean diameter ca 200×10⁻⁶ m,the ratio of the mean diameter of the cellulosic particle body to themean diameter of cellulosic small particles=10). Physiological saline(Otsuka Pharmaceutical Co.) at 23.2% was passed at a linear velocity ofabout 5×10⁻⁴ m/s and 100×10⁻⁹ m³ of a 5-fold dilution of a low-densitylipoprotein reagent (L-2139, SIGMA) in physiological saline was injectedin a pulsating manner. The time course of change in the concentration oflow-density lipoprotein was monitored with an absorptiometer (ATTO) atthe wavelength of 280 nm. As shown in FIG. 19, the peak top position wasdelayed as compared with Comparative Example 5. The particle body usedin this example was a perfusion type particle body (particle bodydiameter ca 200×10⁻⁶ m) comprising cellulose particles (particlediameter 20×10⁻⁶ m) having pores similar to those of the cellulose smallparticle (particle diameter 179×10⁻⁶ m) used in Comparative Example 5.Therefore, the above elution curve was obtained because, even though theparticle diameter of the particle body was large, its perfusionstructure insured a faster mass transfer for low-density lipoproteinwithin the particle body so that the low-density lipoprotein couldmigrate easily within the particle body.

EXAMPLE 9

[0260] As the crosslinked polymer particles, thedivinylbenzene-crosslinked polystyrene carrier HP21 from MitsubishiChemical Co. (Synthetic adsorbent Diaion™ HP21) was used. This HP21 wasdried at room temperature and classified through standard sieves, and afraction measuring 350×10⁻⁶ to 425×10⁻⁶ m with a standard deviation of29% of the mean particle diameter was used. As the organic binder,Styron™ (Asahi Kasei Polystyrene, Grade G8102, Color No. K27, particlesize 71) was used. Methyl ethyl ketone was used as the organic solventwhich does not dissolve crosslinked polymer particles but dissolves theorganic binder.

[0261] The above HP21 in an amount of 16.6 g was put in a 100 ml beakermeasuring 5 cm in diameter and stirred using a mixer (EYELA D. C.STIRRER DOL-RT, Type DCL-2RT; Tokyo Rika Kikai K.K.) with a 3-bladeimpeller (4.9 cm dia.) inserted into the beaker in contact with itsbottom. The number of revolutions was 50 rpm. To crush and trim thecoarse lumps formed in the above stirring granulation, stirring at 500rpm was further carried out for 1 minute. The rotational speed of theimpeller was controlled with a slidac (Yamabishi Electric Co., Ltd.,BS-130-100MC) connected to said stirring mixer.

[0262] Then, under constant stirring, 31 ml of a solution of Styron™ inmethyl ethyl ketone (13 mg/ml) was added. While the stirring wascontinued, methyl ethyl ketone was removed by means of draft suction anda dryer (cold air). The yield of the spherical type bodies thus obtainedwas about 5 weight %. The spherical type bodies were so tough that theydid not collapse under finger pressure.

[0263]FIG. 20 is a light microphotograph [SMZ-10 (Nikon)] showing theparticulate structure of the spherical type body. The spherical typebody was immobilized on a sample station with an electroconductive tapeand subjected to gold/palladium vapor deposition. A scanning electronmicrophotograph of the spherical type body surf ace [ABT-32 (Topcon)] isshown in FIG. 21. It will be apparent from FIG. 21 that the surface ofthe spherical type body showed two areas, namely the organic binder areaand the HP21 surface area. Thus, the presence of the exposed surfaceareas of crosslinked polymer particles which were not covered with theorganic binder could be confirmed. Moreover, on the section of thespherical type body, voids were observed between crosslinked polymerparticles and, in addition, the presence of the organic binder in theinterconnecting parts of the adjoining crosslinked polymer particlescould be confirmed. The above findings indicated that on both thesurface and the section, voids existed between the crosslinked polymerparticles.

EXAMPLE 10

[0264] Carboxymethylcellulose (Wako Pure Chemical Ind. Co.) was mixedwith 6N-NaOH/H₂O to prepare a 2.9 wt. % carboxymethylcellulose solution.A porous cellulose small particle with a mean particle diameter of25×10⁻⁶ m (Chisso Corporation) was suspended in the above aqueouscarboxymethylcellulose-NaOH solution (the percentage of the total volumeof cellulose particles relative to the volume of the suspension=65 vol.%; the percentage of the weight of carboxymethylcellulose relative tothe weight of the suspension=1.0 wt. %) for 5 hours under constantstirring. Then, using a twin-fluid nozzle means (having an inner and anouter nozzle in concentric relation), compressed nitrogen gas wasejected from the outer nozzle while the above suspension was dispensedfrom the inner nozzle into a coagulation bath of 99.5% ethanol to traptherein. The nitrogen gas ejection speed was 3.3×10⁻⁴ m³/s and thesuspension dispensing speed was 1.2×10⁻⁷ m³/s. The diameter of the innernozzle of the twin-fluid nozzle means was 2.6×10⁻³ m, while the diameterof the outer nozzle was 4.4×10⁻³ m. The discharging head was 4 m. Thecarrier thus obtained was rinsed with pure water and wet-classifiedthrough 180×10⁻⁶ m and 355×10⁻⁶ m sieves to provide a carrier having amean particle diameter of 256×10⁻⁶ m.

[0265] After substitution of ethanol for the liquid within the carrier,substitution with 2-methyl-2-propanol was carried out and the carrierwas then lyophilized (Eiko Eng. Co., Ltd.). After vapor deposition ofgold, the lyophilized carrier was examined using a scanning electronmicroscope (Topcon). As shown in FIGS. 22 and 24, the surface andcross-section of the carrier presented with voids (flow-through pores)between the interconnected cellulose particles. Moreover, as shown inFIGS. 23 and 25, small pores (adsorptive pores) could be observed onboth the surface and cross-section of the carrier. The carrier thusobtained had flow-through pores and small spores available foradsorption, thus having a structure such that internal flows occur whenthere is a flow around it.

REFERENCE EXAMPLE 1

[0266] Determination of the Upper-Limit Linear Velocity

[0267] A column having an internal diameter of 10×10⁻³ m and a length of110×10⁻³ m was packed with the carrier obtained in Example 10 (meanparticle diameter 256×10⁻⁶ m), and fresh bovine blood supplemented withcitric acid as an anticoagulant and maintained at 37° C. was passedthrough the column. The blood was introduced at a constant linearvelocity and when the pressure loss became steady, a change was made toa higher linear velocity. In this manner, the upper-limit linearvelocity at which the pressure loss because constant was determined. Asa result, the upper-limit linear velocity was found to be 7.32×10⁻⁴ m/s.

[0268] COMPARATIVE REFERENCE EXAMPLE 1

[0269] Determination of the Upper-Limit Linear Velocity

[0270] Using the commercial carrier POROS™ (Perceptive Biosystems; meanparticle diameter ca 50×10⁻⁶ m), fresh bovine blood was passed and theupper-limit linear velocity at which the pressure loss could be keptconstant was determined as in Reference Example 1. As a result, even atthe initial linear velocity level of 0.75×10⁻⁴ m/s, the pressure lossdid not become steady but continued to rise and ultimately the packedcolumn was plugged with the blood. The experiment was discontinued.

COMPARATIVE REFERENCE EXAMPLE 2

[0271] Determination of the Upper-Limit Linear Velocity

[0272] Using a porous cellulose carrier (Chisso Corporation; meanparticle diameter 220×10⁻⁶ m) which was similar to the celluloseparticles used in Example 10 (mean diameter 25×10⁻⁶ m) in pore geometrybut larger in mean particle diameter, fresh bovine blood was passed andthe upper-limit linear velocity at which the pressure loss could be keptsteady was determined as in Reference Example 1. As a result, theupper-limit linear velocity was found to be 5.78×10⁻⁴ m/s.

[0273] As can be understood from Comparative Reference Example 1, POROS™as a commercial perfusion type carrier was small in particle diameter sothat direct blood perfusion was difficult. On the other hand, thecarrier obtained in Example 10 had a higher upper-limit linear velocityat which the pressure loss could be maintained as can be seen fromReference Example 1. When blood was passed through the columnconventionally used in the purification of body fluids (400×10⁻⁶ m³ involume and 110×10⁻³ m long) at a linear velocity of 7.32×10⁻⁴ m/s, theflow rate was 2.66×10⁻⁶ m³/s (159 ml/min), which falls within thetherapeutic range (0.833×10⁻⁶ to 3.33×10⁻⁶ m³/s (50 to 200 ml/min).

REFERENCE EXAMPLE 2

[0274] Determination of the Elution Curve

[0275] A column (0.01 m in. dia., 0.20 m long) was packed with thecarrier obtained in Example 10 (mean particle diameter ca 256×10⁻⁶ m;the ratio of the mean diameter of the carrier to the mean diameter ofcellulose particles=10). Then, physiological saline (OtsukaPharmaceutical Co.) at 23.2° C. was passed at a linear velocity of about4.6×10⁻⁴ m/s and 100×10⁻⁹ m³ of a 5-fold dilution of a low-densitylipoprotein reagent (SIGMA, L2139) in physiological saline was injectedin a pulsating manner. The time course of change in the concentration oflow-density lipoprotein in the eluate was monitored with anabsorptiometer (ATTO) at the wavelength of 280 nm. The resulting elutioncurve is shown in FIG. 26. The “sita” on the abscissa represents thepercentage of the amount of elution relative to the internal void volumeof the carrier and “E” on the ordinate represents the soluteconcentration obtained by transformation so that the total integral areaof the elution curve would be equal to 1. FIG. 26 shows two peaks. Thefirst peak top is situated immediately following completion of emergenceof the solution corresponding to the internal void volume of the carrier(sita=1) and this peak height was small.

[0276] When albumin (mol. wt. 6.6×10⁴) was injected under the sameconditions as in Reference Example 2, the peak top was situated at“sita”=ca 1.8. Since peaks of an elution curve in the absence ofadsorption are such that a sbstance having a larger molecular weightemerges earlier, the above result indicates that the first peakcorresponds to low-density lipoprotein which has a large molecularweight (mol. wt. 300×10⁴ to 500×10⁴).

COMPARATIVE REFERENCE EXAMPLE 3

[0277] Determination of the Elution Curve

[0278] Using the carrier of Comparative Reference Example 2 (ChissoCorporation; mean particle diameter 220×10⁻⁶ m), the elution curve oflow-density lipoprotein was determined under conditions similar to thoseused in Reference Example 2. The elution curve thus determined is shownin FIG. 27. The first peak top occurred immediately following completionof emergence of the volume of the solution corresponding to theinterparticle void volume of the carrier and its peak height was large.

[0279] With reference to the results in Reference Example 2 andComparative Reference Example 2, the shape of the elution curve inReference Example 2 featured a smaller height of the first peak andtrailing as a whole as compared with the curve obtained in ComparativeReference Example 3. It is, therefore, clear that the carrier of Example10 (mean particle diameter 256×10⁻⁶ m) is superior to the carrier ofComparative Reference Example 3 (mean particle body diameter 220×10⁻⁶ m)with a better mass transfer characteristic.

[0280] It is supposed that despite its having a larger mean particlediameter than the carrier of Comparative Reference Example 3, thecarrier of Example 10 produces a perfusion effect resulting from thepresence of flow-through pores, thus contributing to a faster masstransfer of low-density lipoprotein within the carrier.

[0281] Referring to the elution curves of Reference Example 2 andComparative Reference Example 3, the occurrence of the peak oflow-density lipoprotein immediately following completion of emergence ofthe volume of the solution corresponding to the interparticle voidvolume is not attributable to the absence of pores providing access tothe interior of the carrier but attributable to the fact that because ofthe larger particle size of the carrier, the distance of mass transferis larger so that the low-density lipoprotein does not come intosufficient contact with the carrier particles but emerges out of thecolumn along with the flow down in the interparticle passages of thecolumn packing. The cellulosic small particles constituting the carrierused in Reference Example 2 (mean particle diameter 25×10⁻⁶ m) and thecarrier of Comparative Reference Example 3 (mean particle diameter220×10⁻⁶ m) are similar to each other in pore geometry and receptive tolow-density lipoprotein. The fact that low-density lipoprotein may enterinto those pores has been confirmed by the successful adsorption oflow-density lipoprotein using the carrier of Example 10 in Examples 11and 12.

EXAMPLE 11

[0282] The carrier obtained in Example 10 was reacted withepichlorohydrin at 45° C. for 2 hours and, then, reacted with dextransulfate at 40° C. for 24 hours to provide an adsorbent with dextransulfate immobilized thereon.

[0283] The above adsorbent was added to fresh human serum in a ratio of1 volume, as sediment, to 6 volumes of the serum and the mixture wasshaken at 37° C. for 10 hours. The concentration of the supernatant wasthen measured to calculate the adsorption rate.

Adsorption rate (%)=(concentration of initial liquid−concentration ofsupernatant)/concentration of initial liquid×100

[0284] The adsorption rates of low-density lipoprotein-cholesterol,high-density lipoprotein-cholesterol, and albumin were 51%, 0% and 0%,respectively, indicating that the adsorbent has a specific affinity forlow-density lipoprotein.

EXAMPLE 12

[0285] The carrier obtained in Example 10 was reacted withepichlorohydrin at 45° C. for 2 hours and, then, reacted with aniline at50° C. for 6 hours to provide an adsorbent carrying aniline immobilizedthereon.

[0286] Using the above adsorbent, the adsorption rates were determinedunder the same conditions as in Example 11. The adsorption rates oflow-density lipoprotein-cholesterol, high-densitylipoprotein-cholesterol, and albumin were 55%, 0% and 0%, respectively,indicating the affinity of the adsorbent for low-density lipoprotein.

[0287] It is clear from Examples 11 and 12 that the carrier of Example10 on which a substance having an affinity for a target substance wasimmobilized can be used as an adsorbent.

INDUSTRIAL APPLICABILITY

[0288] The cellulosic particle body according to the first invention andthe perfusion type cellulosic particle body according to the secondinvention, the structures of which have been described hereinbefore,provide for a comparatively large freedom of design in the aspect ofparticle size according to various applications and, depending on thesize and internal structure, can be used with advantage in variousapplications such as gel filtration stationary phases, cellulosic ionexchanger substrates, carriers for affinity chromatography, carriers foradsorption of perfumes and chemicals, supports for immobilization ofmicrobial cells and enzymes, and adsorbent carriers for purification ofbody fluids, among others. The method of producing the cellulosicparticle body of the first invention and the method of producing theperfusion type cellulosic particle body of the second invention, both ofwhich have been described hereinbefore, can be used to easily producesaid cellulosic particle body of the first invention and said perfusiontype cellulosic particle body of the second invention.

[0289] Furthermore, according to the third invention, crosslinkedpolymer particles can be interconnected via an organic binder to providewith ease a novel spherical type body with small restriction to thediameter of crosslinked polymer particles to be interconnected andstructural characteristics that the surfaces of said particles haveareas not covered with the organic binder but remaining exposed.

[0290] The spherical type body according to the third invention, whichhas the above-mentioned structural characteristics, permits effectiveexpression of the properties of crosslinked polymer particles withoutcompromise of their inherent function and therefore finds application asadsorbents in the field of medical care, for example as chromatographiccolumn packings and in body fluid purification systems. The sphericaltype body of this invention can be reused by dissolving out the organicbinder to regenerate the crosslinked polymer particles.

[0291] In addition, the adsorbent for purification of body fluidsaccording to the fourth invention, the construction of which has beendescribed hereinbefore, has a high degree of dynamic adsorptivity sothat it can be expected to reduce the therapeutic treatment time and,hence, improve the patient's quality of life.

1. A cellulosic particle body comprising cellulosic small particleswhich are interconnected and having voids between the cellulosic smallparticles.
 2. The cellulosic particle body according to claim 1 whereinthe cellulosic small particles are interconnected in the presence of abinder.
 3. The cellulosic particle body according to claim 1 or 2wherein the cellulosic small particles have a mean particle diameter of1×10⁻⁶ to 500×10⁻⁶ m.
 4. The cellulosic particle body according to claim1, 2 or 3 wherein the cellulosic small particles are porous particles.5. The cellulosic particle body according to claim 1, 2, 3 or 4 whereinthe particle body has a mean particle diameter of 10×10⁻⁶ to 5000×10⁻⁶m.
 6. A method of producing the cellulosic particle body according toclaim 1 which comprises dispersing cellulosic small particles in analkaline medium and contacting the resulting suspension with acoagulating solution.
 7. The method of producing a cellulosic particlebody according to claim 6 wherein the suspension is formed into dropletsnot exceeding 5×10⁻³ m in diameter and then contacted with thecoagulating solution.
 8. The method of producing a cellulosic particlebody according to claim 6 or 7 wherein a binder is coexistent with thesuspension.
 9. The method of producing a cellulosic particle bodyaccording to claim 8 wherein the suspension has a viscosity of 5×10⁻⁴ to1×10⁴ Pa·s as measured at room temperature.
 10. A perfusion typecellulosic particle body which comprises porous cellulosic smallparticles interconnected to have void between the cellulosic smallparticles as produced by dispersing the porous cellulosic smallparticles in an alkaline medium to prepare a suspension and contactingthe resulting suspension with a coagulating solution.
 11. The perfusiontype cellulosic particle body according to claim 10 wherein thecoagulating solution is an acidic solution.
 12. The perfusion typecellulosic particle body according to claim 11 wherein the alkalinemedium has a pH value of not less than 13, the concentration ofcellulosic small particles in the suspension is 50 to 75 volume %, andthe acidic solution has a pH value of not more than
 1. 13. The perfusiontype cellulosic particle body according to claim 10, 11 or 12 whereinthe ratio of its mean particle diameter to the mean diameter of thecellulosic small particles is less than
 50. 14. The perfusion typecellulosic particle body according to claim 10, 11, 12 or 13 which has amean particle diameter of not less than 100×10⁻⁶ m and, when a housingpacked with it is irrigated at a linear velocity of not less than 3×10⁻⁴m/s, produces a perfusion effect.
 15. A method of producing a perfusiontype cellulosic particle body according to claim 10 wherein porouscellulose particles are dispersed in an alkaline medium to prepare asuspension and the resulting suspension is contacted with a coagulatingsolution.
 16. The method of producing a perfusion type cellulosicparticle body according to claim 15 wherein the coagulating solution isan acidic solution.
 17. The method of producing a perfusion typecellulosic particle body according to claim 16 wherein the alkalinemedium has a pH value of not less than 13, the concentration ofcellulosic small particles in the suspension is 50 to 75 volume % andthe acidic solution has a pH value of not more than
 1. 18. A sphericaltype body which comprises crosslinked polymer particles having diameterswithin a range of 0.1×10⁻⁶ m to 10×10⁻³ m with a standard deviation ofnot greater than 100% of their mean diameter and which has a diameter of1×10⁻⁶ m to 100×10⁻³ m, and satisfies the following conditions (A) to(C): (A) that said crosslinked polymer particles are interconnected viaan organic binder comprising a non-crosslinked polymer; (B) that thesurfaces of said crosslinked polymer particles have area(s) not coveredwith said organic binder but remaining exposed; (C) that voids existbetween the interconnected crosslinked polymer particles.
 19. Thespherical type body comprising the crosslinked polymer particlesaccording to claim 18 wherein the crosslinked polymer particles areporous particles.
 20. The spherical type body comprising crosslinkedpolymer particles according to claim 18 or 19 wherein the crosslinkedpolymer particles are composed of a crosslinked polymer containingstyrene as a monomer unit.
 21. The spherical type body comprising thecrosslinked polymer particles according to claim 18, 19 or 20 whereinthe crosslinked polymer particles are composed of a crosslinked polymercontaining divinylbenzene as a component of crosslinking agent.
 22. Thespherical type body comprising crosslinked polymer particles accordingto claim 18, 19, 20 or 21 wherein the organic binder is anon-crosslinked polymer containing styrene as a monomer unit.
 23. Amethod of producing the spherical type body comprising crosslinkedpolymer particles according to claim 18 which comprises immersingcrosslinked polymer particles having diameters within a range of0.1×10⁻⁶ m to 10×10⁻³ m with a standard deviation of not more than 100%of their mean diameter in a solution containing an organic bindercomprising a non-crosslinked polymer in an organic solvent which doesnot dissolve said crosslinked polymer particles but dissolves saidorganic binder and then evaporating said organic solvent under stirringto interconnect said crosslinked polymer particles via said organicbinder separating out on surfaces of said crosslinked polymer particles.24. An adsorbent for purification of a body fluid which comprises aperfusion type carrier and, as immobilized thereon, a substance havingan affinity for a target substance in the body fluid.
 25. The adsorbentfor purification of a body fluid according to claim 24 wherein theperfusion type carrier comprises the perfusion type cellulosic particlebody according to claim 10, 11, 12, 13 or
 14. 26. The adsorbent forpurification of a body fluid according to claim 24 wherein the perfusiontype carrier is the spherical type body comprising the crosslinkedpolymer particles according to claim 18, 19, 20, 21 or
 22. 27. Theadsorbent for purification of a body fluid according to claim 24, 25 or26 which has a mean particle diameter of not less than 100×10⁻⁶ m andproduces a perfusion effect when a housing packed with it is irrigatedat a linear velocity of not less than 3×10⁻⁴ m/s.
 28. The adsorbent forpurification of a body fluid according to claim 24, 25, 26 or 27 whichcomprises particles having diameters within a range of 100×10⁻⁶ m to4000×10⁻⁶ m and is intended for use in direct contact with whole blood.29. The adsorbent for purification of a body fluid according to claim24, 25, 26, 27 or 28 wherein the ratio of the mean diameter of saidperfusion type particles to the mean diameter of flow-through pores ofthe perfusion type carrier thereof is not greater than
 70. 30. Theadsorbent for purification of a body fluid according to claim 24, 25,26, 27, 28 or 29 wherein the perfusion type carrier has a heightequivalent to a theoretical plate of not greater than 0.5 m asdetermined when it is irrigated with a solution containing a targetsubstance alone at a linear velocity of 1×10⁻⁴ M/s to 10×10⁻⁴ m/s. 31.An adsorption apparatus for purification of a body fluid comprising theadsorbent according to claim 24, 25, 26, 27, 28, 29 or 30 as a packing.32. A method of purifying a body fluid which comprises purifying thebody fluid by means of the adsorption apparatus for purification of thebody fluid according to claim 31.